I wrote a helper script to look for the nmigen bug. Attaching it as a
txt file in case anyone wants to look at it, adapt it, whatever.
Didn't put it in a git repo since I'm not sure it should be there.
save the attached script as a .sh file, run chmod +x on it, then, from
the nmigen repo, run:
git bisect start
git bisect bad 30e2f91176edcd1c8766c2cb11f413b9c77936b9
git bisect good 303ea18cb60567e45a755c6b6289a601f27d46e6
git bisect run ~/projects/nmigen-bisect-script.sh &> ../nmigen-bisect.log

Jacob