rs/SDWebImage — pull request #699 by salling (2014-04-28 07:43:11+00:00)
Title: Race in SDWebImageManager; occasional wrong image.

Do not execute completion block if we've been cancelled. dispatch_main_sync_safe() does not guarantee that no other code runs until our block is executed, so the operation may have been cancelled in-between. If we call the completion block after cancellation, there's a race between this load and the subsequent image load in a table view cell, for instance.