This doesn't fix the problem; I think it is an app problem. It does
improve a bunch of the debugging to help better identify what is going
on, and introduces some checks when adding a fragment to fail
immediately if we are getting into a state when a fragment is going to
be in the added list multiple times (which is pretty much guaranteed
to lead to a failure at some point in the future).
Change-Id: If3a8700763facd61c4505c6ff872ae66875afc8d
f43a33c5ea