Fix back stack problems due to postponed transitions

Bug 38277003

The back stack was being moved while executing operations and
then again when the postponed transaction was executed. It should
only be done once.

Test: Ie47e1f2f158325b9cfd6edb5c40c65d764ff9056
Support Lib Change: I3159c2345a7b77fa82f1c602f4639f51b5a47980

Change-Id: I3b7a032e7e8a9aec565157d42dcaa7232b256ae8