Nightly Dotty workflow of 2022-07-12 failed

[github-actions]

See https://github.com/lampepfl/dotty/actions/runs/2653947851

[griggt]

Seems that Windows doesn't like #15604

In [test_windows_full]

Error:  Failed: Total 462, Failed 4, Errors 0, Passed 458, Ignored 4
Error:  Failed tests:
Error:  	dotty.tools.scripting.BashExitCodeTests
Error:  (scala3-compiler-bootstrapped / Test / testOnly) sbt.TestsFailedException: Tests unsuccessful