[PATCH] git-local-fetch: Avoid calling close(-1)

After open() failure, copy_file() called close(ifd) with ifd == -1
(harmless, but causes Valgrind noise).  The same thing was possible
for the destination file descriptor.

Signed-off-by: Sergey Vlasov <vsu@altlinux.ru>
Signed-off-by: Junio C Hamano <junkio@cox.net>