whs.Create(makeTag("revision", "tag-foo"))
	track.WaitOrdered("revision,tag-foo")
	assert.Equal(t, tw.GetMyTags(), sets.New("revision", "tag-foo"))

	whs.Create(makeTag("revision", "tag-bar"))
	track.WaitOrdered("revision,tag-bar,tag-foo")
	assert.Equal(t, tw.GetMyTags(), sets.New("revision", "tag-foo", "tag-bar"))

	whs.Update(makeTag("not-revision", "tag-bar"))

	defer func() {
		if recover() != nil {
			t = Tag{}
			err = language.ErrSyntax
		}
	}()

	tt, err := language.Parse(s)
	if err != nil {
		return makeTag(tt), err
	}
	tt, changed := canonicalize(c, tt)
	if changed {
		tt.RemakeString()
	}
	return makeTag(tt), err
}

// Compose creates a Tag from individual parts, which may be of type Tag, Base,