Ensure that strcmp() isn't called when head is null.
Previously we were getting segfaults when checkout -B was done from a
detached HEAD.
Signed-off-by: Tay Ray Chuan <rctay89@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Internally, --track and --orphan still use the 'safe' -b, not -B.
Signed-off-by: Tay Ray Chuan <rctay89@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>