code: func (p PartialManifestKey) AddRevision(revision []byte) ManifestKey {
  	var buf bytes.Buffer
  	buf.Write(p)
  	cmpbin.WriteBytes(&buf, revision)
  	return buf.Bytes()
  }
docs: // AddRevision appends a git revision (as bytes) to the PartialManifestKey,
  // returning a full index value for BuildSummary.ManifestKey.