fetch-pack: clear marks before re-marking

If tag following is required when using a transport that does not
support tag following, fetch_pack() will be invoked twice in the same
process, necessitating a clearing of the object flags used by
fetch_pack() sometime during the second invocation. This is currently
done in find_common(), which means that the invocation of
mark_complete_and_common_ref() in do_fetch_pack() is useless.

(This cannot be reproduced with Git alone, because all transports that
come with Git support tag following.)

Therefore, move this clearing from find_common() to its
parent function do_fetch_pack(), right before it calls
mark_complete_and_common_ref().

This has been occurring since the commit that introduced the clearing of
marks, 420e9af498 ("Fix tag following", 2008-03-19).

The corresponding code for protocol v2 in do_fetch_pack_v2() does not
have this problem, as the clearing of flags is done before any marking
(whether by rev_list_insert_ref_oid() or
mark_complete_and_common_ref()).

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

fetch-pack.c

@@ -336,9 +336,6 @@ static int find_common(struct fetch_pack_args *args,
 
 	if (args->stateless_rpc && multi_ack == 1)
 		die(_("--stateless-rpc requires multi_ack_detailed"));
-	if (marked)
-		for_each_ref(clear_marks, NULL);
-	marked = 1;
 
 	for_each_ref(rev_list_insert_ref_oid, NULL);
 	for_each_cached_alternate(insert_one_alternate_object);
@@ -1070,6 +1067,9 @@ static struct ref *do_fetch_pack(struct fetch_pack_args *args,
 	if (!server_supports("deepen-relative") && args->deepen_relative)
 		die(_("Server does not support --deepen"));
 
+	if (marked)
+		for_each_ref(clear_marks, NULL);
+	marked = 1;
 	mark_complete_and_common_ref(args, &ref);
 	filter_refs(args, &ref, sought, nr_sought);
 	if (everything_local(args, &ref)) {