This is useful to ensure that no branch alias is "behind" the most recent tag on the given branch for the alias.
Add to your composer.json in the require-dev section:
"contao-community-alliance/build-system-tool-branch-alias-validation": "~1.0"
Call the binary:
./vendor/bin/validate-branch-alias.php
Optionally pass the root of the git repository to check:
./vendor/bin/validate-branch-alias.php /path/to/some/git/repository