Fix:
```
vendor/github.com/docker/docker/pkg/archive/archive.go:20:2: 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)
```
via:
```
$ git grep -l Sirupsen | xargs sed -i 's:github.com/Sirupsen/logrus:github.com/sirupsen/logrus:g'
```