couchbase-cli crashed when using option server-readd --help

-bash-4.2$ ~/opt/couchbase/bin/couchbase-cli server-readd --help

Traceback (most recent call last):

  File "/home/nonroot/opt/couchbase/lib/python/couchbase-cli", line 20, in <module>

    main()

  File "/home/nonroot/opt/couchbase/lib/python/couchbase-cli", line 14, in main

    args = cli.parse(sys.argv)

  File "/home/nonroot/opt/couchbase/lib/python/cbmgr.py", line 331, in parse

    l2_args = l1_args.klass().parse(args[2:])

  File "/home/nonroot/opt/couchbase/lib/python/cbmgr.py", line 284, in parse

    return self.parser.parse_args(args)

  File "/home/nonroot/opt/couchbase/lib/python/argparse.py", line 1725, in parse_args

    args, argv = self.parse_known_args(args, namespace)

  File "/home/nonroot/opt/couchbase/lib/python/argparse.py", line 1754, in parse_known_args

    namespace, args = self._parse_known_args(args, namespace)

  File "/home/nonroot/opt/couchbase/lib/python/argparse.py", line 1960, in _parse_known_args

    start_index = consume_optional(start_index)

  File "/home/nonroot/opt/couchbase/lib/python/argparse.py", line 1900, in consume_optional

    take_action(action, args, option_string)

  File "/home/nonroot/opt/couchbase/lib/python/argparse.py", line 1828, in take_action

    action(self, namespace, argument_values, option_string)

  File "/home/nonroot/opt/couchbase/lib/python/cbmgr.py", line 250, in __call__

    CBHelpAction._show_man_page(self.klass.get_man_page_name())

  File "/home/nonroot/opt/couchbase/lib/python/cbmgr.py", line 261, in _show_man_page

    call(["man", os.path.join(CB_MAN_PATH, page)])

NameError: global name 'call' is not defined