3dcd49e v2, slightly cheaper

(cherry picked from commit b53cbf467b445a9b57a5567f88a26f77289f7fe1)

src/server/game/Combat/ThreatManager.cpp

@@ -342,10 +342,10 @@ void ThreatManager::AddThreat(Unit* target, float amount, SpellInfo const* spell
         if (!redirInfo.empty())
         {
             float const origAmount = amount;
-            // intentional copy - there's a nested AddThreat call further down that might cause AI calls which cast spells
-            auto const redirects = redirInfo;
-            for (auto const& pair : redirects) // (victim,pct)
+            // intentional iteration by index - there's a nested AddThreat call further down that might cause AI calls which might modify redirect info through spells
+            for (size_t i=0; i<redirInfo.size(); ++i)
             {
+                auto const pair = redirInfo[i]; // (victim,pct)
                 Unit* redirTarget = nullptr;
                 auto it = _myThreatListEntries.find(pair.first); // try to look it up in our threat list first (faster)
                 if (it != _myThreatListEntries.end())