code: def _strip_version_suffix(version):
      
      global version_regex
      if not version:
          return version
      match = version_regex.search(version)
      return match.group(0) if match else version
docs: Remove trailing junk from the version number.
  
      >>> strip_version_suffix('')
      ''
      >>> strip_version_suffix('None')
      'None'
      >>> strip_version_suffix('1.2.3-4trusty-20140131-1359-+0000')
      '1.2.3-4'
      >>> strip_version_suffix('1.2.3-foo')
      '1.2.3'