os: corrupted error from Open on plan9-arm

[bcmills]

#!watchflakes
post <- builder ~ `^plan9` && ` open [^:]+: [^ ]+\s*$`

--- FAIL: TestTransform (4.49s)
    transform_test.go:96: unexpected error from Transform: open /tmp/TestTransform2759707054/blob.bin: '/tmp/TestTransform2759707054/blob.bin' 
FAIL
FAIL	cmd/go/internal/lockedfile	5.123s

The error text here looks truncated. @millerresearch, is this the same sort of corruption you were referring to in #50009 (comment)?

[bcmills]

greplogs --dashboard -md -l -e '\Aplan9-arm.*(?:.*\n)*.* open [^:]+: [^ ]+\s*$'

2022-01-10T17:54:35-933f668/plan9-arm

[millerresearch]

The error text here looks truncated. @millerresearch, is this the same sort of corruption you were referring to in #50009 (comment)?

I think so. As far as I can tell, every Plan 9 filesystem error message should have some explanatory text, not just a bare filename. And there's a space at the end of the line, suggesting there should have been more.

[bcmills]

Looks like these are happening roughly once a month — at least the ones that match the open regexp above.

greplogs -l -e '\Aplan9-arm.*(?:.*\n)*.* open [^:]+: [^ ]+\s*$' --since=2022-01-11
2022-04-06T20:46:47-81ae993/plan9-arm
2022-04-04T21:06:49-5c4ed73/plan9-arm
2022-03-02T17:03:04-4a13f6f/plan9-arm
2022-02-21T21:28:40-c9fe126/plan9-arm

[gopherbot]

Timed out in state WaitingForInfo. Closing.

(I am just a bot, though. Please speak up if this is a mistake or you have the requested information.)