[MERGE][BUG #99983] hooks for commit message editor

[Ian Clatworthy]

Monty Taylor wrote:
> And added the post_commit_message filter hook.
> 

I haven't reviewed all of this but two things stand out ...

bb: resubmit

You need to add some sanity tests.

> +
> +                for hook in Branch.hooks['post_commit_message']:
> +                    try: 
> +                        my_message = hook(my_message)
> +                    except error.CommitMessageInvalid, err:
> +                        raise error.BzrCommandError(str(err))

We don't have a module called "error" - s/error/errors/. That's a good
example of why we ask for tests. :-)

> +post_commit_message
> +-------------------
> +
> +Run after commit message is edited but before ``commit`` is completed. 
> +
> +The hook signature is (my_message) where my_message is the commit message. 
> +The hook should return a string containing the commit message.
> +

You need to explain how a hook can abort the commit if the message
doesn't meet local standards, i.e. mention the CommitMessageInvalid
exception.

Ian C.