path/FastImageCache — pull request #83 by epatey (2014-12-31 17:48:04+00:00)
Title: Fixes a bug that causes image retrieval to never complete if it depends on an source image URL whose request is already in flight.

The bug is that are many scenarios in which `_processImage:forEntity:withFormatName:formatName:completionBlocksDictionary:completionBlocksDictionary` fails to call all completion blocks. Here are the simplest repro steps.
- Formats A and B (neither of which are in a family)
- Entity X
- Both X(A) and X(B) rely on the same source image url
- Retrieve X(A) and then X(B) prior to source image becoming available
- When source image becomes available the image is processed and completion blocks called for A, but not B.

The fix is to redo the calculation of the list of formats that should be processed when a source image becomes available.