Core/Units: Don't set new power type if old power type is the same

src/server/game/Entities/Unit/Unit.cpp

@@ -8635,6 +8635,9 @@ bool Unit::HandleOverrideClassScriptAuraProc(Unit* victim, uint32 /*damage*/, Au
 
 void Unit::setPowerType(Powers new_powertype)
 {
+    if (getPowerType() == new_powertype)
+        return;
+
     SetByteValue(UNIT_FIELD_BYTES_0, 3, new_powertype);
 
     if (GetTypeId() == TYPEID_PLAYER)