mnt: restore shared mounts in a correct shared group

Currently when we have a shared group, we set a source mount for all
of them and then we need to update a source mount when we mount a first
mount from a shared group, because a shared id can be only inherited.
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/mount.c

@@ -1580,7 +1580,9 @@ static int propagate_siblings(struct mount_info *mi)
 	 * to inherite shared group or master id
 	 */
 	list_for_each_entry(t, &mi->mnt_share, mnt_share) {
-		if (t->mounted || t->bind)
+		if (t->mounted)
+			continue;
+		if (t->bind && t->bind->shared_id == t->shared_id)
 			continue;
 		pr_debug("\t\tBind share %s\n", t->mountpoint);
 		t->bind = mi;