code: def _parse_source_line(self, line):
          
          if '--git' in line:
              regex = self.SRC_FILE_RE
          elif '--cc' in line:
              regex = self.MERGE_CONFLICT_RE
          else:
              msg = "Do not recognize format of source in line '{}'".format(line)
              raise GitDiffError(msg)
  
          # Parse for the source file path
          groups = regex.findall(line)
  
          if len(groups) == 1:
              return groups[0]
  
          else:
              msg = "Could not parse source path in line '{}'".format(line)
              raise GitDiffError(msg)
docs: Given a source line in `git diff` output, return the path
          to the source file.