check_aliased_update(): check that dst_name is non-NULL

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>

Author: mhagger

builtin/receive-pack.c

@@ -1081,13 +1081,13 @@ static void check_aliased_update(struct command *cmd, struct string_list *list)
 	if (!(flag & REF_ISSYMREF))
 		return;
 
-	dst_name = strip_namespace(dst_name);
 	if (!dst_name) {
 		rp_error("refusing update to broken symref '%s'", cmd->ref_name);
 		cmd->skip_update = 1;
 		cmd->error_string = "broken symref";
 		return;
 	}
+	dst_name = strip_namespace(dst_name);
 
 	if ((item = string_list_lookup(list, dst_name)) == NULL)
 		return;