Re: [PATCH 06/13] format-patch: use default email for generating message ids

On Sun, May 20, 2012 at 07:58:04PM -0700, Junio C Hamano wrote:

quoted

Technically this is a regression if you really wanted:

  GIT_COMMITTER_EMAIL=some.addr@example.com \
  git format-patch --thread=deep

to make your environment variable part of the message-ids. I don't think
it matters, but I can adjust it if we care.

Is it because you no longer explicitly ask for "committer" and get generic
"who am I" bit from the ident infrastructure?

Right. Calling git_committer_info will also check
getenv("GIT_COMMITTER_EMAIL"), but we don't bother to do that here. We
could change the code to:

  const char *email = getenv("GIT_COMMITTER_EMAIL");
  if (!email)
          email = ident_default_email();

if it matters. I don't think it's worth building an alternate version of
git_committer_info that doesn't do the "name" half of the info.

I wouldn't be surprised if some automated "commit email notification
reacting to push" bot in post-receive hook is using the environment
variable to affect the message ID.  I would doubt that would break the
message as long as the message ID generated from this codepath stays
valid, though, so I wouldn't worry about complaints along the lines of
"you started using names different from what you used to use".  As long as
we don't die due to "Hey bot, you do not seem to have a valid e-mail
address!", I don't think we need to worry about it.

No, we'll never die as a result. But if you have a poorly configured
machine, you might get "user@host.(none)". Or I suppose you could leak
information about the username of the post-receive process. In both
cases, we do this already, so the only change is if you are trying to
override that with GIT_COMMITTER_EMAIL.

So it's a little far-fetched, which is why I didn't bother. But the code
above is quite simple, so maybe it is better to be conservative.

-Peff