cmd/go: internal testsuite errors when -testwork used with 'go test cmd/go'

[thanm]

What version of Go are you using (go version)?

$ go version
go version devel go1.20-a0441c7ae3 Sun Sep 25 01:18:43 2022 +0000 linux/amd64

Does this issue reproduce with the latest release?

yes

What operating system and processor architecture are you using (go env)?

linux/amd64

Problem description

When running the cmd/go package test, the "-testwork" flag seems to result in unexpected errors (in addition to preserving the top level temp dir). Example:

// this works fine
$ go test -test.count=1 -test.run=TestMissingCC .
ok  	cmd/go	0.413s
// now adding -testwork
$ $ go test -testwork -test.count=1 -test.run=TestMissingCC .
--- FAIL: TestMissingCC (0.35s)
    go_test.go:2932: running testgo [list -f {{.Stale}}:{{.StaleReason}} net]
    go_test.go:2932: standard output:
    go_test.go:2932: false:
        
    go_test.go:2938: running testgo [list -f {{.Stale}}:{{.StaleReason}} net]
    go_test.go:2938: standard output:
    go_test.go:2938: false:
        
    go_test.go:2942: internal testsuite error: path(".") with no tempdir
FAIL
exit status 1
FAIL	cmd/go	0.445s
$

Note the internal testsuite error: path(".") with no tempdir message. What's happening here is that for the specific testgo instantiation in this test, it never creates a tempdir subdirectory, and this triggers the error here.

[gopherbot]

Change https://go.dev/cl/434455 mentions this issue: cmd/go: avoid internal errors on "go test -testwork"