Core/Movement: 9080e78 followup

actually port back the previous implementation, now correctly
this implies that a unit that has a different victim than the one its chasing will stand still till either:
- a new movement replaces the current, for w/e reason
- the chase target is again the current victim

probably a pause implementation on the generator is a more elegant solution...

updates #24600

src/server/game/Movement/MovementGenerators/ChaseMovementGenerator.cpp

@@ -26,6 +26,11 @@
 #include "Unit.h"
 #include "Util.h"
 
+static bool HasLostTarget(Unit* owner, Unit* target)
+{
+    return owner->GetVictim() != target;
+}
+
 static bool IsMutualChase(Unit* owner, Unit* target)
 {
     if (target->GetMotionMaster()->GetCurrentMovementGeneratorType() != CHASE_MOTION_TYPE)
@@ -97,8 +102,8 @@ bool ChaseMovementGenerator::Update(Unit* owner, uint32 diff)
     if (!target || !target->IsInWorld())
         return false;
 
-    // the owner might be unable to move (rooted or casting), pause movement
-    if (owner->HasUnitState(UNIT_STATE_NOT_MOVE) || owner->IsMovementPreventedByCasting())
+    // the owner might be unable to move (rooted or casting), or we have lost the target, pause movement
+    if (owner->HasUnitState(UNIT_STATE_NOT_MOVE) || owner->IsMovementPreventedByCasting() || HasLostTarget(owner, target))
     {
         owner->StopMoving();
         _lastTargetPosition.reset();