diff --git a/contrib/source-control-tools/automated-commits.sh b/contrib/source-control-tools/automated-commits.sh
--- a/contrib/source-control-tools/automated-commits.sh
+++ b/contrib/source-control-tools/automated-commits.sh
@@ -79,6 +79,10 @@
 DEVTOOLS_DIR="${TOPLEVEL}"/contrib/devtools
 
 # Make sure tree is clean
+if [ -n "$(git status --porcelain)" ]; then
+  echo "Error: The source tree has unexpected changes. Clean up any changes (try 'git stash') and try again."
+  exit 10
+fi
 git checkout master
 git reset --hard "${PARENT_COMMIT}"