github/ReactiveCocoa — pull request #28 by jspahrsummers (2012-08-07 22:57:27+00:00)
Title: Use NSCondition instead of a semaphore in -firstOrDefault:success:error:

This fixes an issue with signaling the semaphore after it's been released, and also protects against the `value` being replaced more than once.

Includes unit tests.