Github for Mac not showing diffs on code sources

I've been using GitHub for Mac for about a week or so with great success. However, after the auto-update to version 1.2.8, github will no longer show the diffs for me on a .m file:

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It will seem to compare other files, though, for example, a .pbxproj file:

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I have an inkling that somewhere whatever decides can and cannot be compared accidentally got switched to think that .m and .h files aren't comparable.

Solution

This has been fixed as of Github for Mac 1.2.10. Please update your clients.