Use reflog in 'pull --rebase . foo'

Use reflog in 'pull --rebase . foo'

Since c85c792 (pull --rebase: be cleverer with rebased upstream
branches, 2008-01-26), "git pull --rebase" has used the reflog to try to
rebase from the old upstream onto the new upstream.

Make this work if the local repository is explicitly passed on the
command line as in 'git pull --rebase . foo'.

Signed-off-by: Martin von Zweigbergk <martin.von.zweigbergk@gmail.com>
Acked-by: Santi Béjar <santi@agolina.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>