Moving a Copy of an Actor from Persistent to Sublevel Dirties Persistent Level

Using Alt-Drag to move a copy of an actor from the persistent level to a sublevel (when the sublevel is selected as the current level in the Levels window), the persistent level is getting marked as dirty.

Clarification: This does not only affect the persistent level. This will also affect a sublevel if the object is moved from SublevelA to SublevelB, for example.

Found: 4.17.1

Reproduced: 4.16.3 and 4.18 Main CL# 359616

1. Open the editor
2. Create two levels (LevelA and LevelB)
3. Open Level A and Save All
4. Open the Levels window (Window->Levels)
5. In the Levels window, select Levels->Add Existing and add Level B as a sublevel
6. Select the Persistent Level as the Current Level (double-click on it)
7. Add a cube to the Persistent Level and Save the level
8. Back in the Levels window, select LevelB as the Current Level (double-click on it)
9. Back in the viewport, Alt-Drag to copy the cube into the sublevel

Result: The persistent level gets marked as dirty

Expected: Only the sublevel would get marked as dirty.