cmd/go: spurious recursive VCS reference using Mercurial

[philpennock]

Please answer these questions before submitting your issue. Thanks!

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

go 1.9.1, and confirmed issue not present with go 1.9

Does this issue reproduce with the latest release?

yes

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

GOHOSTARCH="amd64"
GOHOSTOS="darwin"

It's Darwin 16.7.0 from macOS 10.12.6 but problem also observed in Linux docker images under Circle CI, so it appears to be platform independent.

What did you do?

I ran go get -v -u -t -d ./... twice on a project which pulls in bitbucket.org/pkg/inflect as a dependency. When run with a clean tree, it succeeds without error. When run with the content already checked out, it errors. Across 385 lines of output from the above, there is one line of difference between the two:

-bitbucket.org/pkg/inflect (download)
+package bitbucket.org/pkg/inflect: directory "/Users/pdp/tmp/go-foo/src/bitbucket.org/pkg/inflect" uses hg, but parent "/Users/pdp/tmp/go-foo/src/bitbucket.org/pkg" uses hg

There is no .hg directory in the parent. This error appears spurious.

If I switch /usr/local/go from 1.9.1 back to 1.9, then go get -v -u -t -d ./... succeeds.

Thus 1.9.1 appears to be incorrectly determining that the parent is using hg and that this is some kind of conflict.

What did you expect to see?

No error, no difference between the two runs

What did you see instead?

A spurious failure.

[ianlancetaylor]

I can recreate this by doing

go get bitbucket.org/pkg/inflect
go get -u bitbucket.org/pkg/inflect

The error I get is

package bitbucket.org/pkg/inflect: directory "/home/iant/gopath/src/bitbucket.org/pkg/inflect" uses hg, but parent "/home/iant/gopath/src/bitbucket.org/pkg" uses hg

There is no .hg directory in /home/iant/gopath/src/bitbucket.org/pkg nor in /home/iant/gopath/src/bitbucket.org. There is a .hg directory in /home/iant/gopath/src/bitbucket.org/pkg/inflect.

CC @rsc

[gopherbot]

Change https://golang.org/cl/69670 mentions this issue: cmd/go: correct directory used in checkNestedVCS test

[ianlancetaylor]

Reopening for 1.9.2.

[rsc]

CL 69670 OK for Go 1.9.2.

[gopherbot]

Change https://golang.org/cl/70839 mentions this issue: [release-branch.go1.8] cmd/go: correct directory used in checkNestedVCS test

[gopherbot]

Change https://golang.org/cl/70984 mentions this issue: [release-branch.go1.9] cmd/go: correct directory used in checkNestedVCS test

[rsc]

go1.9.2 has been packaged and includes:

• CL 69670

The release is posted at golang.org/dl.

— golang.org/x/build/cmd/releasebot, Oct 26 21:09:22 UTC