When async operations are executed in Editor mode (not playing any scenes), isDone never returns 'true', unless the Editor or any of its windows are resized.

Steps to reproduce:
1) Open the attached project.
2) In the menu bar, go to Async Repro > Test it!.
- The console logs indicate that the operation finished successfully.
3) Repeat step 2 once more.
- The console logs indicate that the operation hasn't finished yet.

A coroutine, executing the AsyncOperation hangs, because isDone is never set to 'true' for that operation. This reproduces consistently, except for the first time after Editor launch.
The operation finishes as soon as any of the Editor windows are resized.

Reproduced:
2017.1.0a6, 5.2.2f1