e32e00d (git-p4: better message for "git-p4 sync" when not
cloned, 2011-02-19) broke another use case, that of using
"git-p4 sync" to import a new branch into an existing repository.
Refine the fix again, on top of the fix in ac34efc.
Reported-by: Michael Horowitz <michael.horowitz@ieee.org> Signed-off-by: Pete Wyckoff <pw@padd.com> Tested-by: Michael Horowitz <michael.horowitz@ieee.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>