Several issues here:
- Hooks can't invoke shell scripts on Windows, so use sh to launch
- dd in MSYS only recognizes status=noxfer
- The PATH updating triggered a massive slowdown, but is no longer needed
I have no idea why, but removing the PATH update substantially increased the
speed of the test. It was running finishing at ~4:30 with --debug and ~14:50
without it, but now completes in ~2:20 on my Windows laptop.