xdist handles Ctrl-C (keyboard interrupt) poorly

Basic info

• Commit SHA: any
• Platform: windows

Bug description

When running the CI tests locally before committing, we notice that if we Ctrl-C out of a xdist load balanced test at some point, the next time we run the test xdist fails again and is still angry about Keyboard interruption.

It persists through reboots and even shows up in a new clean clone. Xdist has somehow stored its error state somewhere. I tried deleting all kinds of caches and tmp files and got it working again (but don't know exactly how) but now it happens to other colleagues as well.

Ways to reproduce

$ python -m pytest tests -v --update_ref 1 -m create_ref $ [press Ctrl-C during test run several times to kill all the running threads]

next run: $ python -m pytest tests -v --update_ref 1 -m create_ref

tests/test_param_file.py::test_param_file_tests[TD stereo at 16.4 kbps, 32kHz in, 16kHz out, DTX on]

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! xdist.dsession.Interrupted: received keyboard-interrupt !!!!