From: Phil Hord <hordp@cisco.com>
Date: Tue, 23 Oct 2012 20:39:56 +0000 (-0400)
Subject: git-pull: Avoid merge-base on detached head
X-Git-Tag: v1.8.0.1~16^2
X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/e980765c59c173e9a10ce1069c763645b87fd50c?hp=e980765c59c173e9a10ce1069c763645b87fd50c

git-pull: Avoid merge-base on detached head

git pull --rebase does some clever tricks to find the base
for $upstream, but it forgets that we may not have any
branch at all.  When this happens, git merge-base reports its
"usage" help in the middle of an otherwise successful
rebase operation, because git-merge is called with one too
few parameters.

Since we do not need the merge-base trick in the case of a
detached HEAD, detect this condition and bypass the clever
trick and the usage noise.

Signed-off-by: Phil Hord <hordp@cisco.com>
Signed-off-by: Jeff King <peff@peff.net>
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