Core/Groups: Fixed UnitIsPartyLeader lua function

src/server/game/Entities/Player/Player.cpp

@@ -18494,6 +18494,9 @@ void Player::_LoadGroup(PreparedQueryResult result)
     {
         if (Group* group = sGroupMgr->GetGroupByDbStoreId((*result)[0].GetUInt32()))
         {
+            if (group->IsLeader(GetGUID()))
+                SetFlag(PLAYER_FLAGS, PLAYER_FLAGS_GROUP_LEADER);
+
             uint8 subgroup = group->GetMemberGroup(GetGUID());
             SetGroup(group, subgroup);
             if (getLevel() >= LEVELREQUIREMENT_HEROIC)
@@ -18504,6 +18507,9 @@ void Player::_LoadGroup(PreparedQueryResult result)
             }
         }
     }
+
+    if (!GetGroup() || !GetGroup()->IsLeader(GetGUID()))
+        RemoveFlag(PLAYER_FLAGS, PLAYER_FLAGS_GROUP_LEADER);
 }
 
 void Player::_LoadBoundInstances(PreparedQueryResult result)

src/server/game/Groups/Group.cpp

@@ -99,6 +99,7 @@ bool Group::Create(Player* leader)
     m_guid = MAKE_NEW_GUID(lowguid, 0, HIGHGUID_GROUP);
     m_leaderGuid = leaderGuid;
     m_leaderName = leader->GetName();
+    leader->SetFlag(PLAYER_FLAGS, PLAYER_FLAGS_GROUP_LEADER);
 
     if (isBGGroup() || isBFGroup())
         m_groupType = GROUPTYPE_BGRAID;
@@ -666,6 +667,10 @@ void Group::ChangeLeader(uint64 newLeaderGuid)
         CharacterDatabase.CommitTransaction(trans);
     }
 
+    if (Player* oldLeader = ObjectAccessor::FindPlayer(m_leaderGuid))
+        oldLeader->RemoveFlag(PLAYER_FLAGS, PLAYER_FLAGS_GROUP_LEADER);
+
+    newLeader->SetFlag(PLAYER_FLAGS, PLAYER_FLAGS_GROUP_LEADER);
     m_leaderGuid = newLeader->GetGUID();
     m_leaderName = newLeader->GetName();
     ToggleGroupMemberFlag(slot, MEMBER_FLAG_ASSISTANT, false);