Hmmph. The adafruit_blinka library is broken, I know *exactly* why, and I have NO WAY to tell anyone. This is a fine kettle of fish that Adafruit has created for themselves, and this problem will not be discovered soon.
Somebody will have to try to use Adafruit Circuitpython libraries in Linux in order for this problem to be discovered. Since it apparently has not been discovered yet, I am just guessing that I am the first person to try this. I could be wrong about this though.