Allow display of custom message when no-commit-to-branch fails

This change should make the failures of no-commit-to-branch easier
for people that might encounter it as maintainers can provide
information about allowed branch names. Current behavior just gives
an opaque error that is not very useful for people that do not have
a lot of knowledge about the project they are contributing to.

Author: ssbarnea

pre_commit_hooks/no_commit_to_branch.py

@@ -37,11 +37,20 @@ def main(argv: Sequence[str] | None = None) -> int:
             'may be specified multiple times'
         ),
     )
+    parser.add_argument(
+        '-m', '--message', default='',
+        help=(
+            'What message to display if the the check fails'
+        ),
+    )
     args = parser.parse_args(argv)
 
     protected = frozenset(args.branch or ('master', 'main'))
     patterns = frozenset(args.pattern or ())
-    return int(is_on_branch(protected, patterns))
+    result = int(is_on_branch(protected, patterns))
+    if result:
+        print(args.message)
+    return result
 
 
 if __name__ == '__main__':