Bug - properly reorg fragment saved state on dataset change

Steps to reproduce original behavior:

* Turn on "don't keep activities" in developer options
* Open a chat
* Turn on OTR
* Go to home and wait a few seconds for activity to be iced
* Go back to chat
* Close chat
* Open another chat

Old behavior: the OTR state will be set to checked, causing ChatView to negotiate OTR by way of the CheckedChanged callback.

New behavior: OTR remains off.

Hopefully this also resolve the issue that Nathan experienced with OTR checked state being shown as off when it's on.