ReactiveCocoa/ReactiveCocoa — pull request #1415 by vmartinelli (2014-07-18 01:48:34+00:00)
Title: The disposable was not added, so it was never called (Swift beta 3)

The value inside `_disposables` was not equal to `ds` (that is a copy, not a reference), so `d` was added to `ds` and not to `_disposables` value; therefore the `d` disposable was never called.