Core/Arena: Fix a typo made by me in revision b468981513. You can now join Arena again.

--HG--
branch : trunk

src/server/game/Groups/Group.cpp

@@ -1626,7 +1626,7 @@ GroupJoinBattlegroundResult Group::CanJoinBattlegroundQueue(Battleground const*
     BattlegroundQueueTypeId bgQueueTypeIdRandom = BattlegroundMgr::BGQueueTypeId(BATTLEGROUND_RB, 0);
 
     // check every member of the group to be able to join
-    memberscount = 1;
+    memberscount = 0;
     for (GroupReference *itr = GetFirstMember(); itr != NULL; itr = itr->next(), ++memberscount)
     {
         Player *member = itr->getSource();