cmd/go: TestNewReleaseRebuildsStalePackagesInGOPATH failing

[cagedmantis]

Go version

tip

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

Long test builders

What did you do?

Ran the long test builders.

What did you expect to see?

Passing tests

What did you see instead?

After the submission of go.dev/cl/516860, this failure started happening on the long test builders.

vcs-test.golang.org rerouted to http://127.0.0.1:50422
https://vcs-test.golang.org rerouted to https://127.0.0.1:50423
go test proxy running at GOPROXY=http://127.0.0.1:50424/mod
--- FAIL: TestNewReleaseRebuildsStalePackagesInGOPATH (13.54s)
    go_test.go:953: running testgo [install p1]
    go_test.go:953: standard error:
    go_test.go:953: ../../../../tmp/cmd-go-test-5767483697673610539/gotest11850510197277294159/goroot/src/runtime/rand.go:10:2: cannot find package "internal/chacha8rand" in any of:
        	/tmp/buildlet/tmp/cmd-go-test-5767483697673610539/gotest11850510197277294159/goroot/src/internal/chacha8rand (from $GOROOT)
        	/tmp/buildlet/tmp/cmd-go-test-5767483697673610539/gotest11850510197277294159/d1/src/internal/chacha8rand (from $GOPATH)
        
    go_test.go:953: go [install p1] failed unexpectedly in /tmp/buildlet/go/src/cmd/go: exit status 1
FAIL
FAIL	cmd/go	1824.812s

@golang/release @rsc @bcmills

[gopherbot]

Change https://go.dev/cl/547995 mentions this issue: cmd/go: avoid hard-coding runtime dependencies in TestNewReleaseRebuildsStalePackagesInGOPATH