Fix a bug where restartLoader would result in a stuck loader

Framework edition

In some cases restartLoader calls that happen in quick succession
could cause the new loader to become stuck and never run. Treat loader
restarts for loaders that have not yet started the same as starting a
brand new loader.

Bug 27437287
https://code.google.com/p/android/issues/detail?id=56464

Change-Id: Ia4e276fc8e63d43b9c52c6155cea827b194d8b19