If there is an error in resolve_ref_unsafe(), it returns NULL. We check
for this case, but not until after calling strip_namespace(). Instead,
call strip_namespace() *after* the NULL check.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: David Turner <dturner@twopensource.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>