Perform git commit description style check on shorter hashes (e.g. 7 symbols)

[Lord-KA]

GitHub has basically set it's own standard for commit shortened hash lengths - 7 first symbols, e.g. 5f6d367c51f7545a940119e7a393baf982b80f3f is being displayed as 5f6d367. While our codestyle requires first 12 symbols and commit subject, the according test isn't being performed on 7-sym hashes.