Ports from (https://github.com/TrinityCore/TrinityCore)

Core/Unit: don't clear low health aura states on death
Core/Gossip: Fix gossip bug on modify money
Core/Spells: Change the radius of PBAoEs following the feedback received on
Core/Player: update interaction checks, some info taken from client
Core/Spell: abort channeling if no valid targets are found after searching
Core/Creature: fix _DespawnAtEvade saving wrong respawn time
Core/Spell: fixed some problems with per caster aura states
Quickfix a bug introduced by 2f19d97 which prevented GTAoE from being cast.
Core/SmartAI: allow SMART_ACTION_SEND_GOSSIP_MENU to override default gossip
Core/Spell: in case of immunity, check all effects to choose correct procFlags, as none has technically hit
Fix evade issues when a spell hits the target just before evading.
Scripts/Command: implement .debug play music command
Partial revert, Unit::getAttackerForHelper() shouldn't return units that we aren't in combat with (victim can be such a unit for players/player pets, which can startattack from a distance without entering combat).
Fix an issue where CanSpawn would never get invoked on creatures without per-guid script.
Core/Players: fix null dereference crash

Source/Game/Spells/SpellEffects.cs

@@ -2452,8 +2452,7 @@ namespace Game.Spells
 
             // this effect use before aura Taunt apply for prevent taunt already attacking target
             // for spell as marked "non effective at already attacking target"
-            if (unitTarget == null || !unitTarget.CanHaveThreatList()
-                || unitTarget.GetVictim() == m_caster)
+            if (!unitTarget.CanHaveThreatList() || unitTarget.GetVictim() == m_caster)
             {
                 SendCastResult(SpellCastResult.DontReport);
                 return;