Looks good to me. I checked it against the core PR, and current Core code.

Re-comment auto-test generating #define
Rebase on master

In the review of D3100, @markblundeberg had suggested renaming the flag. This Diff does that.

Fix description nit and rebase.

Improve comments in checkdatasig_tests.cpp

Remove test bloat.
Make comments in checkdatasig_tests.cpp more precise.
Rebase on master.

Added duplicate CHECKDATASIG tests with flag off to script_tests.cpp to generate auto test cases.

In D3100#73242, @markblundeberg wrote:

I'm also thinking that maybe all the script tests that include the CHECKDATASIG script flag should stop referring to it, except for tests of sigops counting. However if other implementations are relying on those flags being in script_tests.json then maybe they should be kept.

Remove redundant brackets and rebase.

Added IBD to test plan

Rebase on non-broken D3063

Fix stupid mistake.

need to fix build

Rebase on D3063 changes.

Simplify boolean logic per Mark's suggestion.

@deadalnix I tried to address your comments by changing the test in D3063 and then rebasing this Diff on top of that one.

Fix rebase

Rebased on top of test changes.

Add test for CHECKDATASIG inclusion in standard or mandatory flags.

@deadalnix I spoke with Florian recently, and he said he will be away for the next 30 days.

Add CHECKDATASIG to standard flags, not to mandatory flags.

I realized it makes more sense to combine the code and test changes together in one Diff.

Checked on my local node, parameters look good.

I just realized this overlaps with @florian's D2506

rebase

Seems to cover everything of note.

Looks good.

Checks out against my local node.

After more investigation and discussion, I have decided to add banning exception, and re-implement the test based on the recent Schnorr and Segwit Recovery.

Work in progress
NULLDUMMY activation ported to Graviton
tests updated to work with recent refactors
To Do: check node banning behavior

Work in progress

Going to try to revive this for Nov 2019 Upgrade

I compared it against my home node, parameters check out.