all: Azure go-autorest causing ambiguous import

[zombiezen]

@clausti just encountered this error while trying to build on a PR:

build gocloud.dev/samples/gocdk-pubsub: cannot load github.com/Azure/go-autorest/tracing: ambiguous import: found github.com/Azure/go-autorest/tracing in multiple modules:
	github.com/Azure/go-autorest v11.3.2+incompatible (/Users/clausti/go/pkg/mod/github.com/!azure/go-autorest@v11.3.2+incompatible/tracing)
	github.com/Azure/go-autorest/tracing v0.1.0 (/Users/clausti/go/pkg/mod/github.com/!azure/go-autorest/tracing@v0.1.0)

(Similar to #1958)

[eliben]

Exact reproduction steps? (@clausti ?)

Seems to work for me calling go build in samples/gocdk-pubsub. Tried clearing modcache and re-running, still works

[clausti]

I was working on the branch for this PR, but I don't recall exactly what proceeded it, and it's not repro-ing for me now, either.

We can reopen if anyone else sees it?

[zombiezen]

@jba has seen it:

build gocloud.dev/samples/gocdk-pubsub: cannot load github.com/Azure/go-autorest/tracing: ambiguous import: found github.com/Azure/go-autorest/tracing in multiple modules:                                                                  
        github.com/Azure/go-autorest v12.0.0+incompatible (/usr/local/google/home/jba/go/pkg/mod/github.com/!azure/go-autorest@v12.0.0+incompatible/tracing)                                                                                 
        github.com/Azure/go-autorest/tracing v0.1.0 (/usr/local/google/home/jba/go/pkg/mod/github.com/!azure/go-autorest/tracing@v0.1.0)