diff --git a/.arclint b/.arclint
index 5e2af14b7..f3c9f5683 100644
--- a/.arclint
+++ b/.arclint
@@ -1,215 +1,216 @@
 {
     "linters": {
         "generated": {
             "type": "generated"
         },
         "clang-format": {
             "type": "clang-format",
             "version": ">=8.0",
             "bin": ["clang-format-8", "clang-format"],
             "include": "(^src/.*\\.(h|c|cpp|mm)$)",
             "exclude": [
                 "(^src/(secp256k1|univalue|leveldb)/)"
             ]
         },
         "autopep8": {
             "type": "autopep8",
             "version": ">=1.3.4",
             "include": "(\\.py$)",
             "flags": [
                 "--aggressive",
                 "--ignore=W503,W504"
             ]
         },
         "flake8": {
             "type": "flake8",
             "version": ">=3.0",
             "include": "(\\.py$)",
             "flags": [
                 "--ignore=E501,E704,W503,W504"
             ]
         },
         "lint-format-strings": {
             "type": "lint-format-strings",
             "include": "(^src/.*\\.(h|c|cpp)$)",
             "exclude": [
                 "(^src/(secp256k1|univalue|leveldb)/)"
             ]
         },
         "check-doc": {
             "type": "check-doc",
             "include": "(^src/.*\\.(h|c|cpp)$)"
         },
         "lint-tests": {
             "type": "lint-tests",
             "include": "(^src/(seeder/|rpc/|wallet/)?test/.*\\.(cpp)$)"
         },
         "lint-python-format": {
             "type": "lint-python-format",
             "include": "(\\.py$)",
             "exclude": [
                 "(^test/lint/lint-python-format\\.py$)"
             ]
         },
         "phpcs": {
             "type": "phpcs",
             "include": "(\\.php$)",
             "exclude": [
                 "(^arcanist/__phutil_library_.+\\.php$)"
             ],
             "phpcs.standard": "arcanist/phpcs.xml"
         },
         "lint-locale-dependence": {
             "type": "lint-locale-dependence",
             "include": "(^src/.*\\.(h|cpp)$)",
             "exclude": [
                 "(^src/(crypto/ctaes/|leveldb/|secp256k1/|tinyformat.h|univalue/))"
             ]
         },
         "lint-cheader": {
             "type": "lint-cheader",
             "include": "(^src/.*\\.(h|cpp)$)",
             "exclude": [
                 "(^src/(crypto/ctaes|secp256k1|univalue|leveldb)/)"
             ]
         },
         "spelling": {
             "type": "spelling",
             "exclude": [
                 "(^build-aux/m4/)",
                 "(^depends/)",
                 "(^doc/release-notes/)",
                 "(^src/(qt/locale|secp256k1|univalue|leveldb)/)",
                 "(^test/lint/dictionary/)"
             ],
             "spelling.dictionaries": [
                 "test/lint/dictionary/english.json"
             ]
         },
         "lint-assert-with-side-effects": {
             "type": "lint-assert-with-side-effects",
             "include": "(^src/.*\\.(h|cpp)$)",
             "exclude": [
                 "(^src/(secp256k1|univalue|leveldb)/)"
             ]
         },
         "lint-include-quotes": {
             "type": "lint-include-quotes",
             "include": "(^src/.*\\.(h|cpp)$)",
             "exclude": [
                 "(^src/(secp256k1|univalue|leveldb)/)"
             ]
         },
         "lint-include-guard": {
             "type": "lint-include-guard",
             "include": "(^src/.*\\.h$)",
             "exclude": [
                 "(^src/(crypto/ctaes|secp256k1|univalue|leveldb)/)",
                 "(^src/tinyformat.h$)"
             ]
         },
         "lint-include-source": {
             "type": "lint-include-source",
             "include": "(^src/.*\\.(h|c|cpp)$)",
             "exclude": [
                 "(^src/(secp256k1|univalue|leveldb)/)"
             ]
         },
         "lint-stdint": {
             "type": "lint-stdint",
             "include": "(^src/.*\\.(h|c|cpp)$)",
             "exclude": [
                 "(^src/(secp256k1|univalue|leveldb)/)",
                 "(^src/compat/assumptions.h$)"
             ]
         },
         "lint-source-filename": {
             "type": "lint-source-filename",
             "include": "(^src/.*\\.(h|c|cpp)$)",
             "exclude": [
                 "(^src/(secp256k1|univalue|leveldb)/)"
             ]
         },
         "lint-boost-dependencies": {
             "type": "lint-boost-dependencies",
             "include": "(^src/.*\\.(h|cpp)$)"
         },
         "check-rpc-mappings": {
             "type": "check-rpc-mappings",
             "include": "(^src/(rpc/|wallet/rpc).*\\.cpp$)"
         },
         "lint-python-encoding": {
             "type": "lint-python-encoding",
             "include": "(\\.py$)"
         },
         "lint-python-shebang": {
             "type": "lint-python-shebang",
             "include": "(\\.py$)",
             "exclude": [
                 "(__init__\\.py$)"
             ]
         },
         "lint-bash-shebang": {
             "type": "lint-bash-shebang",
             "include": "(\\.sh$)"
         },
         "shellcheck": {
             "type": "shellcheck",
+            "version": ">=0.7.0",
             "flags": [
                 "--external-sources",
                 "--source-path=SCRIPTDIR"
             ],
             "include": "(\\.sh$)",
             "exclude": [
                 "(^src/(secp256k1|univalue)/)"
             ]
         },
         "lint-shell-locale": {
             "type": "lint-shell-locale",
             "include": "(\\.sh$)",
             "exclude": [
                 "(^src/(secp256k1|univalue)/)"
             ]
         },
         "lint-cpp-void-parameters": {
             "type": "lint-cpp-void-parameters",
             "include": "(^src/.*\\.(h|cpp)$)",
             "exclude": [
                 "(^src/(crypto/ctaes|secp256k1|univalue|leveldb)/)",
                 "(^src/compat/glibc_compat.cpp$)"
             ]
         },
         "lint-logs": {
             "type": "lint-logs",
             "include": "(^src/.*\\.(h|cpp)$)"
         },
         "lint-qt": {
             "type": "lint-qt",
             "include": "(^src/qt/.*\\.(h|cpp)$)",
             "exclude": [
                 "(^src/qt/(locale|forms|res)/)"
             ]
         },
         "lint-doxygen": {
             "type": "lint-doxygen",
             "include": "(^src/.*\\.(h|c|cpp)$)",
             "exclude": [
                 "(^src/(crypto/ctaes|secp256k1|univalue|leveldb)/)"
             ]
         },
         "lint-whitespace": {
             "type": "lint-whitespace",
             "include": "(\\.(ac|am|cmake|conf|in|include|json|m4|md|openrc|php|pl|sh|txt|yml)$)",
             "exclude": [
                 "(^src/(secp256k1|univalue|leveldb)/)"
             ]
         },
         "lint-cppcheck": {
             "type": "lint-cppcheck",
             "include": "(^src/.*\\.(h|c|cpp)$)",
             "exclude": [
                 "(^src/(crypto/ctaes|secp256k1|univalue|leveldb)/)"
             ]
         }
     }
 }
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 70da7296a..b1006e3a1 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -1,218 +1,231 @@
 Contributing to Bitcoin ABC
 ===========================
 
 The Bitcoin ABC project welcomes contributors!
 
 This guide is intended to help developers contribute effectively to Bitcoin ABC.
 
 Communicating with Developers
 -----------------------------
 
 To get in contact with ABC developers, we monitor a telegram supergroup.  The
 intent of this group is specifically to facilitate development of Bitcoin-ABC,
 and to welcome people who wish to participate.
 
 https://t.me/joinchat/HCYr50mxRWjA2uLqii-psw
 
 Acceptable use of this supergroup includes the following:
 
 * Introducing yourself to other ABC developers.
 * Getting help with your development environment.
 * Discussing how to complete a patch.
 
 It is not for:
 
 * Market discussion
 * Non-constructive criticism
 
 Bitcoin ABC Development Philosophy
 ----------------------------------
 
 Bitcoin ABC aims for fast iteration and continuous integration.
 
 This means that there should be quick turnaround for patches to be proposed,
 reviewed, and committed. Changes should not sit in a queue for long.
 
 Here are some tips to help keep the development working as intended. These
 are guidelines for the normal and expected development process. Developers
 can use their judgement to deviate from these guidelines when they have a
 good reason to do so.
 
 - Keep each change small and self-contained.
 - Reach out for a 1-on-1 review so things move quickly.
 - Land the Diff quickly after it is accepted.
 - Don't amend changes after the Diff accepted, new Diff for another fix.
 - Review Diffs from other developers as quickly as possible.
 - Large changes should be broken into logical chunks that are easy to review,
 and keep the code in a functional state.
 - Do not mix moving stuff around with changing stuff. Do changes with renames
 on their own.
 - Sometimes you want to replace one subsystem by another implementation,
 in which case it is not possible to do things incrementally. In such cases,
 you keep both implementations in the codebase for a while, as described
 [here](https://www.gamasutra.com/view/news/128325/Opinion_Parallel_Implementations.php)
 - There are no "development" branches, all Diffs apply to the master
 branch, and should always improve it (no regressions).
 - Don't break the build, it is important to keep master green as much as possible.
 If a Diff is landed, and breaks the build, fix it quickly. If it cannot be fixed
 quickly, it should be reverted, and re-applied later when it no longer breaks the build.
 - As soon as you see a bug, you fix it. Do not continue on. Fixing the bug becomes the
 top priority, more important than completing other tasks.
 - Automate as much as possible, and spend time on things only humans can do.
 
 Here are some handy links for development practices aligned with Bitcoin ABC:
 
 - [Developer Notes](doc/developer-notes.md)
 - [Statement of Bitcoin ABC Values and Visions](https://www.yours.org/content/bitcoin-abc---our-values-and-vision-a282afaade7c)
 - [How to Do Code Reviews Like a Human - Part 1](https://mtlynch.io/human-code-reviews-1/)
 - [How to Do Code Reviews Like a Human - Part 2](https://mtlynch.io/human-code-reviews-2/)
 - [Large Diffs Are Hurting Your Ability To Ship](https://medium.com/@kurtisnusbaum/large-diffs-are-hurting-your-ability-to-ship-e0b2b41e8acf)
 - [Stacked Diffs: Keeping Phabricator Diffs Small](https://medium.com/@kurtisnusbaum/stacked-diffs-keeping-phabricator-diffs-small-d9964f4dcfa6)
 - [Parallel Implementations](https://www.gamasutra.com/view/news/128325/Opinion_Parallel_Implementations.php)
 - [The Pragmatic Programmer: From Journeyman to Master](https://www.amazon.com/Pragmatic-Programmer-Journeyman-Master/dp/020161622X)
 - [Advantages of monolithic version control](https://danluu.com/monorepo/)
 - [The importance of fixing bugs immediately](https://youtu.be/E2MIpi8pIvY?t=16m0s)
 - [Slow Deployment Causes Meetings](https://www.facebook.com/notes/kent-beck/slow-deployment-causes-meetings/1055427371156793/)
 - [Good Work, Great Work, and Right Work](https://forum.dlang.org/post/q7u6g1$94p$1@digitalmars.com)
 - [Accelerate: The Science of Lean Software and DevOps](https://www.amazon.com/Accelerate-Software-Performing-Technology-Organizations/dp/1942788339)
 
 Getting set up with the Bitcoin ABC Repository
 ----------------------------------------------
 
 1. Create an account at https://reviews.bitcoinabc.org/
 
 2. Install Git and Arcanist on your machine
 
 Git documentation can be found at: https://git-scm.com/
 
 Arcanist documentation can be found at:
 https://secure.phabricator.com/book/phabricator/article/arcanist_quick_start/
 
 And: https://secure.phabricator.com/book/phabricator/article/arcanist/
 
 To install these packages on Debian or Ubuntu, type: `sudo apt-get install git arcanist`
 
 3. If you do not already have an SSH key set up, follow these steps:
 
 Type: `ssh-keygen -t rsa -b 4096 -C "your_email@example.com"`
 
 Enter a file in which to save the key (/home/*username*/.ssh/id_rsa): [Press enter]
 
 4. Upload your SSH public key to reviews.bitcoinabc.org
 
   - Go to: `https://reviews.bitcoinabc.org/settings/user/*username*/page/ssh/`
 
   - Under "SSH Key Actions", Select "Upload Public Key"
 
 Paste contents from: `/home/*username*/.ssh/id_rsa.pub`
 
 5. Clone the repository and install Arcanist certificate:
 
 ```
 git clone ssh://vcs@reviews.bitcoinabc.org:2221/source/bitcoin-abc.git
 
 cd bitcoin-abc
 
 arc install-certificate
 ```
 
 Note: Arcanist tooling will tend to fail if your remote origin is set to something other
 than the above.  A common mistake is to clone from Github and then forget to update
 your remotes.
 
 Follow instructions provided by `arc install-certificate` to provide your API token.
 
 6. Code formatting tools
 
 During submission of patches, arcanist will automatically run `arc lint` to
 enforce Bitcoin ABC code formatting standards, and often suggests changes.
 If code formatting tools do not install automatically on your system, you
 will have to install the following:
 
 On Ubuntu (>= 18.04+updates) or Debian (>= 10):
 ```
-sudo apt-get install clang-format-8 clang-tidy-8 clang-tools-8 cppcheck python-autopep8 flake8 php-codesniffer shellcheck
+sudo apt-get install clang-format-8 clang-tidy-8 clang-tools-8 cppcheck python-autopep8 flake8 php-codesniffer
 ```
 
 If not available in the distribution, `clang-format-8` and `clang-tidy` can be
 installed from https://releases.llvm.org/download.html or https://apt.llvm.org.
 
 For example, for macOS:
 ```
 curl http://releases.llvm.org/8.0.0/clang+llvm-8.0.0-x86_64-apple-darwin.tar.xz | tar -xJv
 ln -s $PWD/clang+llvm-8.0.0-x86_64-apple-darwin/bin/clang-format /usr/local/bin/clang-format
 ln -s $PWD/clang+llvm-8.0.0-x86_64-apple-darwin/bin/clang-tidy /usr/local/bin/clang-tidy
 ```
 
+If you are modifying a shell script, you will need to install the `shellcheck` linter.
+A recent version is required and may not be packaged for your distribution.
+Standalone binaries are available for download on the project's github release page:
+https://github.com/koalaman/shellcheck/releases
+
+If you are running Debian 10, it is also available in the backports repository:
+```
+echo "deb http://deb.debian.org/debian buster-backports main" | sudo tee -a /etc/apt/sources.list
+sudo apt-get update
+sudo apt-get -t buster-backports install shellcheck
+```
+
+
 Working with The Bitcoin ABC Repository
 ---------------------------------------
 
 A typical workflow would be:
 
 - Create a topic branch in Git for your changes
 
     git checkout -b 'my-topic-branch'
 
 - Make your changes, and commit them
 
     git commit -a -m 'my-commit'
 
 - Create a differential with Arcanist
 
     arc diff
 
 You should add suggested reviewers and a test plan to the commit message.
 Note that Arcanist is set up to look only at the most-recent commit message,
 So all you changes for this Diff should be in one Git commit.
 
 - For large changes, break them into several Diffs, as described in this
 [guide](https://medium.com/@kurtisnusbaum/stacked-diffs-keeping-phabricator-diffs-small-d9964f4dcfa6).
 You can also include "Depends on Dxxx" in the Arcanist message to indicate
 dependence on other Diffs.
 
 - Log into Phabricator to see review and feedback.
 
 - Make changes as suggested by the reviewers. You can simply edit the files
 with my-topic-branch checked out, and then type `arc diff`. Arcanist will
 give you the option to add uncommited changes. Or, alternatively, you can
 commit the changes using `git commit -a --am` to add them to the last commit,
 or squash multiple commits by typing `git rebase -i master`. If you squash,
 make sure the commit message has the information needed for arcanist (such
 as the Diff number, reviewers, etc.).
 
 - Update your Diff by typing `arc diff` again.
 
 - When reviewers approve your Diff, it should be listed as "ready to Land"
 in Phabricator. When you want to commit your diff to the repository, check out
 type my-topic-branch in git, then type `arc land`. You have now successfully
 committed a change to the Bitcoin ABC repository.
 
 - When reviewing a Diff, apply the changeset on your local by using
 `arc patch D{NNNN}`
 
 - You will likely be re-writing git histories multiple times, which causes
 timestamp changes that require re-building a significant number of files. It's
 highly recommended to install `ccache` (re-run cmake if you install it
 later), as this will help cut your re-build times from several minutes to under
 a minute, in many cases.
 
 What to work on
 ---------------
 
 If you are looking for a useful task to contribute to the project, a good place
 to start is the list of tasks at https://reviews.bitcoinabc.org/maniphest/
 
 You could also try [backporting](doc/backporting.md) some code from Bitcoin Core.
 
 Copyright
 ---------
 
 By contributing to this repository, you agree to license your work under the
 MIT license unless specified otherwise in `contrib/debian/copyright` or at
 the top of the file itself. Any work contributed where you are not the original
 author must contain its license header with the original author(s) and source.
 
 Disclosure Policy
 -----------------
 
 See [DISCLOSURE_POLICY](DISCLOSURE_POLICY.md).
diff --git a/arcanist/linter/ShellCheckLinter.php b/arcanist/linter/ShellCheckLinter.php
index 8f34d735d..aa25bba7f 100644
--- a/arcanist/linter/ShellCheckLinter.php
+++ b/arcanist/linter/ShellCheckLinter.php
@@ -1,87 +1,98 @@
 <?php
 
 /**
  * Uses the ShellCheck tool to run static analysis on shell scripts
  */
 final class ShellCheckLinter extends ArcanistExternalLinter {
   const SHELLCHECK_EXCLUDED_RULES = array(
     // phpcs:disable Generic.Files.LineLength.TooLong
     // phpcs:disable Generic.Files.LineLength.MaxExceeded
     'SC1117', // Backslash is literal in "\.". Prefer explicit escaping: "\\.".
     'SC2046', // Quote this to prevent word splitting.
     'SC2086', // Double quote to prevent globbing and word splitting.
     'SC2162', // read without -r will mangle backslashes.
     // phpcs:enable
   );
 
   const SHELLCHECK_SEVERITY_MAP = array(
       'note' => ArcanistLintSeverity::SEVERITY_ADVICE,
       'warning' => ArcanistLintSeverity::SEVERITY_WARNING,
       'error' => ArcanistLintSeverity::SEVERITY_ERROR,
   );
 
   public function getInfoName() {
     return 'shellcheck';
   }
 
   public function getInfoDescription() {
     return pht('Use shellcheck for processing specified files.');
   }
 
   public function getLinterName() {
     return 'SHELLCHECK';
   }
 
   public function getLinterConfigurationName() {
     return 'shellcheck';
   }
 
   public function getDefaultBinary() {
     return 'shellcheck';
   }
 
   public function getInstallInstructions() {
     return pht('Make sure shellcheck is in directory specified by $PATH');
   }
 
   public function shouldExpectCommandErrors() {
     return true;
   }
 
+  public function getVersion() {
+    list($stdout) = execx('%C --version', $this->getExecutableCommand());
+
+    $regex = '/^version: (?P<version>\d+\.\d+\.\d+)/m';
+    if (preg_match($regex, $stdout, $matches)) {
+      return $matches['version'];
+    }
+
+    return false;
+  }
+
   protected function getMandatoryFlags() {
     return array(
       '--format=gcc',
       '--exclude='.implode(',', self::SHELLCHECK_EXCLUDED_RULES));
   }
 
   private function getSeverity($severity) {
     if (array_key_exists($severity, self::SHELLCHECK_SEVERITY_MAP)) {
       return self::SHELLCHECK_SEVERITY_MAP[$severity];
     }
 
     return ArcanistLintSeverity::SEVERITY_ERROR;
   }
 
   protected function parseLinterOutput($path, $err, $stdout, $stderr) {
     $messages = array();
 
     $pattern = '/(.+):(\d+):(\d+): (.+): (.+) \[(SC\d+)\]/';
     if (preg_match_all($pattern, $stdout, $errors, PREG_SET_ORDER)) {
       foreach ($errors as $error) {
         list(, $file, $line, $char, $severity, $message, $code) = $error;
 
         $messages[] = id(new ArcanistLintMessage())
         ->setGranularity(ArcanistLinter::GRANULARITY_FILE)
         ->setPath($path)
         ->setLine($line)
         ->setChar($char)
         ->setCode($code)
         ->setSeverity($this->getSeverity($severity))
         ->setName('ShellCheck found an issue:')
         ->setDescription($message);
       }
     }
 
     return $messages;
   }
 }
diff --git a/contrib/teamcity/setup-debian-buster.sh b/contrib/teamcity/setup-debian-buster.sh
index 58393f89c..662585734 100755
--- a/contrib/teamcity/setup-debian-buster.sh
+++ b/contrib/teamcity/setup-debian-buster.sh
@@ -1,109 +1,116 @@
 #!/usr/bin/env bash
 
 export LC_ALL=C.UTF-8
 
 set -euxo pipefail
 
 dpkg --add-architecture i386
 
 PACKAGES=(
   arcanist
   automake
   autotools-dev
   binutils
   bsdmainutils
   build-essential
   ccache
   cmake
   cppcheck
   curl
   flake8
   g++-aarch64-linux-gnu
   g++-arm-linux-gnueabihf
   git
   g++-mingw-w64
   gnupg
   gperf
   imagemagick
   jq
   lcov
   less
   lib32stdc++-8-dev
   libboost-all-dev
   libbz2-dev
   libc6-dev:i386
   libcap-dev
   libdb++-dev
   libdb-dev
   libevent-dev
   libjemalloc-dev
   libminiupnpc-dev
   libprotobuf-dev
   libqrencode-dev
   libqt5core5a
   libqt5dbus5
   libqt5gui5
   librsvg2-bin
   libssl-dev
   libtiff-tools
   libtinfo5
   libtool
   libzmq3-dev
   make
   ninja-build
   nsis
   php-codesniffer
   pkg-config
   protobuf-compiler
   python3
   python3-autopep8
   python3-setuptools
   python3-zmq
   qemu-user-static
   qttools5-dev
   qttools5-dev-tools
-  shellcheck
   software-properties-common
   tar
   wget
   wine
 )
 
 function join_by() {
   local IFS="$1"
   shift
   echo "$*"
 }
 
 apt-get update
 DEBIAN_FRONTEND=noninteractive apt-get install -y $(join_by ' ' "${PACKAGES[@]}")
 
+BACKPORTS=(
+  shellcheck
+)
+
+echo "deb http://deb.debian.org/debian buster-backports main" | tee -a /etc/apt/sources.list
+apt-get update
+DEBIAN_FRONTEND=noninteractive apt-get -t buster-backports install -y $(join_by ' ' "${BACKPORTS[@]}")
+
 TEAMCITY_DIR=$(dirname "$0")
 
 # FIXME this should no longer be needed starting with Teamcity 2020.1, which
 # supports Java 11.
 "${TEAMCITY_DIR}/install_openjdk8.sh"
 
 # Install llvm-8 and clang-10
 apt-key add "${TEAMCITY_DIR}"/llvm.pub
 add-apt-repository "deb https://apt.llvm.org/buster/   llvm-toolchain-buster-8  main"
 add-apt-repository "deb https://apt.llvm.org/buster/   llvm-toolchain-buster-10  main"
 apt-get update
 
 LLVM_PACKAGES=(
   clang-8
   clang-10
   clang-format-8
   clang-tidy-8
   clang-tools-8
 )
 DEBIAN_FRONTEND=noninteractive apt-get install -y $(join_by ' ' "${LLVM_PACKAGES[@]}")
 update-alternatives --install /usr/bin/clang clang "$(command -v clang-8)" 100
 update-alternatives --install /usr/bin/clang++ clang++ "$(command -v clang++-8)" 100
 # Use a lower priority to keep clang-8 the default
 update-alternatives --install /usr/bin/clang clang "$(command -v clang-10)" 50
 update-alternatives --install /usr/bin/clang++ clang++ "$(command -v clang++-10)" 50
 
 # Use the mingw posix variant
 update-alternatives --set x86_64-w64-mingw32-g++ $(command -v x86_64-w64-mingw32-g++-posix)
 update-alternatives --set x86_64-w64-mingw32-gcc $(command -v x86_64-w64-mingw32-gcc-posix)