Re: `b4 prep` "not a prep-managed branch" error with changed Git email

On Fri, 27 Mar 2026 16:22:03 +0100, Miguel Ojeda wrote:
> Igor (in Cc) contacted me since he was having a blocking issue with
> `b4 prep` to send a v2 of a patch series. He was consistently getting
> the following error:
> 
>   CRITICAL: This is not a prep-managed branch.
> 
> I don't use the `prep` subcommand myself, but I tried it and couldn't
> reproduce it, so I suggested contacting you with a reproducer, and in
> order to do so, I suggested getting the Git log `--fuller` of the
> branch. Then I noticed he had a different committer than the
> Signed-off-by -- I recalled he was changing his email recently in
> another patch to `MAINTAINERS`.
> 
> And, indeed, if I changed my Git `user.email` I could reproduce the
> issue. In Igor's side, the actual trigger was that for v2 of that
> patch series he was adding an entry to the `.mailmap`, i.e. the
> effective Git user email that appears in `git log` is what counts.
> 
> Is it intended? If so, could perhaps `b4` suggest that may be the
> cause in the error message? (or even check that is indeed the issue)

Yes, it's not intended but it's a known gotcha that I haven't fixed yet.  
It's a side-effect of a guard that I hastily put in place after the time 
when a prep branch got merged into linux-next by accident and broke "b4 
prep" for everyone.

I've added this to the bug tracker now (using the spaking new "b4 bugs"
app) and I'll work to show a better error message and a way to recover 
from this condition.

Thanks,
-- 
KR