[Godeps] Specifying source tag fails to stage

[Nicholas Skaggs]

$ snapcraft
Preparing to pull juju
Pulling juju
From https://github.com/juju/juju
 * tag juju-2.0.2 -> FETCH_HEAD
fatal: update_ref failed for ref 'HEAD': cannot update the ref 'HEAD': Trying to write non-commit object 6f9a7321d050cc4318d009330854c781e027a7cb to branch refs/heads/master
Command '['git', '-C', '/home/nskaggs/projects/juju/classic-juju-snap/parts/juju/src', 'pull', '--recurse-submodules=yes', 'https://github.com/juju/juju.git', 'refs/tags/juju-2.0.2']' returned non-zero exit status 128

My part for this snapcraft.yaml looks like this:

parts:
  juju:
    plugin: godeps
    go-importpath: github.com/juju/juju
    source: https://github.com/juju/juju.git
    source-type: git
    build-packages: [gcc]
    source-tag: juju-2.0.2

I will note the source is pulled and is correct in the parts directory. However, snapcraft fails per above.