The original code for viewlayer collection flag syncing across moves
from D9158 didn't consider the case where the collection could no longer
be found in its original view layer (moving a collections betwen scenes).
The fix is to just check if the collection starts in the same scene as
it will be moved to before trying to do the flag syncing. I thought about
this for a while and tried a couple other solutions, but I couldn't come
up with a proper way to support syncing the layer collection flags across
scenes without making too many changes.
Differential Revision: https://developer.blender.org/D9568
c645da98d8