We parse the command-line arguments into a refspec struct, but we never
free them. We should do so before exiting to avoid triggering the
leak-checker.
This triggers in t5540 many times (basically every invocation of
http-push).
Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>