cmd/go: hang in 'exec powershell' in TestScript/build_acl_windows on windows/arm64

[bcmills]

greplogs --dashboard -md -l -e 'FAIL: TestScript/build_acl_windows .*(?:\n .*)*\> exec powershell.*(?:\n .*)*: test timed out while running command' --since=2019-03-08

2022-02-12T05:44:16-f14ad78/windows-arm64-11
2022-02-11T22:01:05-badba35/windows-arm64-10

[bcmills]

It's curious that the only two failures occurred within a few hours of each other — close enough that the coordinator could have been running them concurrently. It kind of makes me wonder whether something in the PowerShell executable is non-hermetic. 🤔

This test was converted to a script test in CL 165752 (2019-03-08), so the test itself is fairly old. Since these are the first time we've seen this failure mode, I'm going to leave this test enabled to see whether any future failures are also time-correlated.

(CC @alexbrainman @zx2c4 in case they have any insights.)

[bcmills]

greplogs -l -e 'FAIL: TestScript/build_acl_windows .*(?:\n .*)*\> exec powershell.*(?:\n .*)*: test timed out while running command' --since=2022-02-13
2022-02-16T21:18:03-39d2f50/windows-arm64-10

But none since then. 🤔

[qmuntal]

It kind of makes me wonder whether something in the PowerShell executable is non-hermetic.

Looking at the logs, I think the hang happens while running go build -o $TMP\main.exe main.go, so before powershell is executed.