Re: [BUG] branch renamed to 'HEAD'

[Junio C Hamano <gitster@pobox.com>]

Jacob Keller <jacob.keller@gmail.com> writes:

> What about changing interpret-branch-name gains a flag to return a
> fully qualified ref rather than returning just the name? That seems
> like it would be more reasonable behavior.

There are two kinds of callers to i-b-n.  The ones that want a local
branch name because they are parsing special places on the command
line that using a local branch name makes difference (as opposed to
using any extended SHA-1 expression), like "git checkout master"
(which means different thing from "git checkout master^0").  And the
ones that can use any object name.

It depends on how your flag works, but if it means "add refs/heads/
when you got a local branch name", then that would not work well for
the former callers, as end-user inputs @{-1} and refs/heads/master
would become indistinguishable.  The former is expanded to 'master'
(if you were on that branch) and ends up being refs/heads/master.
"git checkout refs/heads/master" would be (unless you have a branch
with that name, i.e. refs/heads/refs/heads/master) a request to
detach HEAD at the commit, but the user wanted to be on the previous
branch.  And the latter iclass of callers are probably already happy
with or without the flag, so they won't be helped, either.

A flag to affect the behaviour (as opposed to &flag as a secondary
return value, like Peff's patch does) can be made to work.  Perhaps
a flag that says "keep the input as is if the result is not a local
branch name" would pass an input "@" intact and that may be
sufficient to allow "git branch -m @" to rename the current branch
to "@" (I do not think it is a sensible rename, though ;-).  But
probably some callers need to keep the original input and compare
with the result to see if we expanded anything if we go that route.
At that point, I am not sure if there are much differences in the
ease of use between the two approaches.