message: options: Fix regexp used in parsing glued options.
diff: @@ -199,7 +199,7 @@ class Drake:
  foo => (None, None)
  '''
  - match = re.match('--(?P<opt>\\w+)(?=(?P<arg>.*))?', arg)
  + match = re.match('--(?P<opt>\\w+)(?:=(?P<arg>.*))?', arg)
  if not match:
  match = re.match('-(?P<opt>\\w)(?P<arg>.+)?', arg)
  if match:
  