When we 'git rebase $upstream', git uses 'rev-parse --verify
$current_branch' to find ORIG_HEAD. But if $current_branch
is ambiguous, 'rev-parse --verify' emits a warning and returns
a SHA1 anyway. When the wrong ambiguous choice is used,
git-rebase fails non-gracefully: it emits a warning about
failing to lock $current_branch, an error about being unable to
checkout $current_branch again, and it might even decide the
rebase is a fast-forward when it is not.
In the 'rebase $upstream' case, we already know the unambiguous
spelling of $current_branch is "HEAD". Fix git-rebase to find
Add a test in t3400-rebase.sh which creates an ambiguous branch
name and rebases it implicitly with 'git rebase $other'.
Signed-off-by: Phil Hord <firstname.lastname@example.org>
Signed-off-by: Junio C Hamano <email@example.com>