I generated my own meta-repo with metatools to do some testing. When I did a world update, I noticed alsa-lib is failing because the patch "alsa-lib-1.1.6-missing_files.patch" is missing. I checked the ebuild and realized it's looking for the patch in media-sound/files/alsa-lib in core-kit, but the patch is currently placed in media-libs/alsa-lib/files. I'm not sure I understand the structure completely, but I suppose the solution is to just move the patch in the appropriate place.