branch: remove negative exit code

Replace an instance of "exit(-1)" with "exit(1)". We don't use negative
exit codes - they are misleading because Unix machines will coerce them
to 8-bit unsigned values, losing the sign.

Signed-off-by: Glen Choo <chooglen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: chooglen

branch.c

@@ -263,7 +263,7 @@ static void setup_tracking(const char *new_ref, const char *orig_ref,
 		string_list_append(tracking.srcs, orig_ref);
 	if (install_branch_config_multiple_remotes(config_flags, new_ref,
 				tracking.remote, tracking.srcs) < 0)
-		exit(-1);
+		exit(1);
 
 cleanup:
 	string_list_clear(&tracking_srcs, 0);