Commands run:
```
$ gvt delete github.com/docker/docker/pkg/archive
$ gvt fetch -revision 239d61f04bf1c00273c1c89b531fe37993e08a9f github.com/moby/moby/pkg/archive
$ make clean ; make  # build failure
$ gvt delete github.com/docker/docker/pkg/fileutils
$ gvt fetch -revision 239d61f04bf1c00273c1c89b531fe37993e08a9f github.com/moby/moby/pkg/fileutils
$ make clean ; make  # build failure
$ gvt delete github.com/docker/docker/pkg/stdcopy
$ gvt fetch -revision 239d61f04bf1c00273c1c89b531fe37993e08a9f github.com/moby/moby/pkg/stdcopy
```
N.B.: following this commit, build fails with:
```
vendor/github.com/weaveworks/common/backoff/backoff.go:6:2: cannot find package "github.com/Sirupsen/logrus" in any of:
	/go/src/github.com/weaveworks/scope/vendor/github.com/Sirupsen/logrus (vendor tree)
	/usr/local/go/src/github.com/Sirupsen/logrus (from $GOROOT)
	/go/src/github.com/Sirupsen/logrus (from $GOPATH)
vendor/github.com/docker/docker/pkg/archive/archive.go:19:2: cannot find package "github.com/docker/docker/pkg/fileutils" in any of:
	/go/src/github.com/weaveworks/scope/vendor/github.com/docker/docker/vendor/github.com/docker/docker/pkg/fileutils (vendor tree)
	/go/src/github.com/weaveworks/scope/vendor/github.com/docker/docker/pkg/fileutils
	/usr/local/go/src/github.com/docker/docker/pkg/fileutils (from $GOROOT)
	/go/src/github.com/docker/docker/pkg/fileutils (from $GOPATH)
vendor/github.com/fsouza/go-dockerclient/client.go:35:2: cannot find package "github.com/docker/docker/pkg/stdcopy" in any of:
	/go/src/github.com/weaveworks/scope/vendor/github.com/docker/docker/pkg/stdcopy (vendor tree)
	/usr/local/go/src/github.com/docker/docker/pkg/stdcopy (from $GOROOT)
	/go/src/github.com/docker/docker/pkg/stdcopy (from $GOPATH)
```
Resolution in subsequent commit.