ReactiveCocoa/ReactiveCocoa — pull request #1500 by jspahrsummers (2014-09-22 22:11:56+00:00)
Title: Use an unsafe self reference in -[RACSubscriber init]

A weak reference is unnecessarily expensive (in terms of memory growth _and_ latency, both related to the global weak reference table), and this disposable block is guaranteed to be run before the `RACSubscriber` disappears.