Fix tag following

Before the second fetch-pack connection in the same process, unmark
all of the objects marked in the first connection, in order that we'll
list them as things we have instead of thinking we've already
mentioned them.

Signed-off-by: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-fetch-pack.c

@@ -26,6 +26,8 @@ static const char fetch_pack_usage[] =
 #define SEEN		(1U << 3)
 #define POPPED		(1U << 4)
 
+static int marked;
+
 /*
  * After sending this many "have"s if we do not get any new ACK , we
  * give up traversing our history.
@@ -61,6 +63,16 @@ static int rev_list_insert_ref(const char *path, const unsigned char *sha1, int
 	return 0;
 }
 
+static int clear_marks(const char *path, const unsigned char *sha1, int flag, void *cb_data)
+{
+	struct object *o = deref_tag(parse_object(sha1), path, 0);
+
+	if (o && o->type == OBJ_COMMIT)
+		clear_commit_marks((struct commit *)o,
+				   COMMON | COMMON_REF | SEEN | POPPED);
+	return 0;
+}
+
 /*
    This function marks a rev and its ancestors as common.
    In some cases, it is desirable to mark only the ancestors (for example
@@ -153,6 +165,10 @@ static int find_common(int fd[2], unsigned char *result_sha1,
 	unsigned in_vain = 0;
 	int got_continue = 0;
 
+	if (marked)
+		for_each_ref(clear_marks, NULL);
+	marked = 1;
+
 	for_each_ref(rev_list_insert_ref, NULL);
 
 	fetching = 0;