anchor.diff:      return _shaRegEx.hasMatch(value);
     }
   
  -  static List<GitReference> parseLsRemoteOutput(String input) {
  +  static List<CommitReference> parseLsRemoteOutput(String input) {
       assert(input != null);
       final lines = Util.splitLines(input);
   
  
positive.code:           final match = _lsRemoteRegExp.allMatches(line).single;
            assert(match.groupCount == 2);
  
            return new GitReference(match[1], match[2]);
  
          }).toList();
    }
  
negative.code: /**
   * Represents the output from `git ls-remote`
   */
  class CommitReference {
    final String sha;
    final String reference;
  
    CommitReference(this.sha, this.reference) {
      assert(Git.isValidSha(sha));
  
      assert(reference != null);
  