- restored the original implementation of DONTOVERLAP, because Heretic depends on it being somewhat broken.

A side effect of the incorrect implementation is that Gargoyles hitting other Gargoyles won't call P_DamageMobj.

src/p_interaction.cpp

@@ -1545,7 +1545,7 @@ dopain:
 				target->SetState (target->SeeState);
 			}
 		}
-		else if ((damage > 0 || fakedPain) && source != target->target && target->OkayToSwitchTarget (source))
+		else if (source != target->target && target->OkayToSwitchTarget (source))
 		{
 			// Target actor is not intent on another actor,
 			// so make him chase after source

src/p_map.cpp

@@ -1298,7 +1298,7 @@ bool PIT_CheckThing(FMultiBlockThingsIterator &it, FMultiBlockThingsIterator::Ch
 				if ((tm.thing->Z() >= topz) || (tm.thing->Top() <= thing->Z()))
 					return true;
 			}
-			// If they are not allowed to overlap, the rest of this function still needs to be executed.
+			else return unblocking;	// This may not really make sense, but Heretic depends on the broken implementation.
 		}
 	}