x/build: TryBots for golang.org/dl subrepo place code at wrong location

[bcmills]

The TryBot run for https://golang.org/cl/167703 failed, and the failure appears to be spurious.

Looking at the error message, it appears that the builder is running at $GOPATH/src/golang.org/x/dl, but the actual repo path does not have the /x component. That causes the build to fail in GOPATH mode, since internal imports cannot be resolved.

CC @dmitshur @bradfitz

linux-amd64 at aa193c0b9623acd7397c0799ffc9efe5845216b2 building dl at 1fd72ee045448e802db0932c08bf55095b3992f8

:: Running /workdir/go/bin/go with args ["/workdir/go/bin/go" "test" "-short" "golang.org/x/dl/..."] and env ["PATH=/workdir/go/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin" "HOSTNAME=buildlet-linux-jessie-rnef69983" "DEBIAN_FRONTEND=noninteractive" "HOME=/root" "USER=root" "GO_STAGE0_NET_DELAY=0s" "GO_STAGE0_DL_DELAY=100ms" "WORKDIR=/workdir" "GOROOT_BOOTSTRAP=/workdir/go1.4" "GO_BUILDER_NAME=linux-amd64" "GOROOT_BOOTSTRAP=/go1.4" "GO_DISABLE_OUTBOUND_NETWORK=1" "GOROOT=/workdir/go" "GOPATH=/workdir/gopath" "GOPROXY=http://10.240.0.49:30156" "GO111MODULE=auto" "TMPDIR=/workdir/tmp" "GOCACHE=/workdir/gocache"] in dir /workdir/gopath/src/golang.org/x/dl

go1.10/main.go:20:8: cannot find package "golang.org/dl/internal/version" in any of:
	/workdir/go/src/golang.org/dl/internal/version (from $GOROOT)
	/workdir/gopath/src/golang.org/dl/internal/version (from $GOPATH)


Error: tests failed: exit status 1

[bradfitz]

Yeah, "dl" is a special case. So far all the "subrepos" (legacy hg term) became golang.org/x/$foo, but not dl.

[gopherbot]

Change https://golang.org/cl/170417 mentions this issue: cmd/coordinator: fix trybots for the "dl" repo

[gopherbot]

Change https://golang.org/cl/212023 mentions this issue: cmd/coordinator: fix trybots for the "dl" repo more