AiFollow: return from execute() if target is not player (Fixes #1637)

apps/openmw/mwmechanics/aifollow.cpp

@@ -39,6 +39,11 @@ bool MWMechanics::AiFollow::execute (const MWWorld::Ptr& actor,float duration)
     if (target.isEmpty())
         return true; //Target doesn't exist
 
+    // Only the player can be actively followed. AiFollow packages with targets other than the player
+    // are only used for defining combat alliances, since NPCs will defend whoever they are following or being followed by.
+    if (target != MWBase::Environment::get().getWorld()->getPlayerPtr())
+        return false;
+
     actor.getClass().getCreatureStats(actor).setDrawState(DrawState_Nothing);
 
     ESM::Position pos = actor.getRefData().getPosition(); //position of the actor