That is the same conclusion I came to at the time, that it made no sense. I wondered if linux-firmware didn't change somewhere in there. As I recall, 3.13 uses the -8 firmware, and 3.15 used the -9, and I wondered if -9 might have been updated. I can retry 3.15.0-rc1 -rc2 -rc3 if that would be helpful to you.
That is the same conclusion I came to at the time, that it made no sense. I wondered if linux-firmware didn't change somewhere in there. As I recall, 3.13 uses the -8 firmware, and 3.15 used the -9, and I wondered if -9 might have been updated. I can retry 3.15.0-rc1 -rc2 -rc3 if that would be helpful to you.