Core/Spells Make certain spells (e.g. Mind Control) properly flag the caster for PvP (#17145)

* This issue was caused by PvP-flagging being done calculated after the target's flag was turned off by becoming a pet.

(cherry picked from commit e7a12edb833ffe26f27d6e392e97a560ffb0c827)

src/server/game/Spells/Spell.cpp

@@ -2356,8 +2356,13 @@ void Spell::DoAllEffectOnTarget(TargetInfo* target)
     PrepareScriptHitHandlers();
     CallScriptBeforeHitHandlers(missInfo);
 
+    bool enablePvP = false; // need to check PvP state before spell effects, but act on it afterwards
+
     if (spellHitTarget)
     {
+        // if target is flagged for pvp also flag caster if a player
+        if (unit->IsPvP() && m_caster->GetTypeId() == TYPEID_PLAYER)
+            enablePvP = true; // Decide on PvP flagging now, but act on it later.
         SpellMissInfo missInfo2 = DoSpellHitOnUnit(spellHitTarget, mask, target->scaleAura);
 
         if (missInfo2 != SPELL_MISS_NONE)
@@ -2511,8 +2516,7 @@ void Spell::DoAllEffectOnTarget(TargetInfo* target)
         // Needs to be called after dealing damage/healing to not remove breaking on damage auras
         DoTriggersOnSpellHit(spellHitTarget, mask);
 
-        // if target is fallged for pvp also flag caster if a player
-        if (unit->IsPvP() && m_caster->GetTypeId() == TYPEID_PLAYER)
+        if (enablePvP)
             m_caster->ToPlayer()->UpdatePvP(true);
 
         CallScriptAfterHitHandlers();