python - Docopt: 繰り返し要素の後のオプションは、繰り返し要素として解釈されます

Question

単純な Python プログラムでdocoptを使用しています。

#!/usr/bin/env python
"""
Farmers market

Usage:
  farmersmarket.py buy -i <item> -q <quantity> [<quantity>] [-p <price>] [-dvh]
  farmersmarket.py -d | --debug
  farmersmarket.py -v | --version
  farmersmarket.py -h | --help

Options:
  -i --item         Item.
  -q --quantity     Quantity.
  -p --price        Price.
  -d --debug        Show debug messages.
  -h --help         Show this screen.
  -v --version      Show version.
"""

from docopt import docopt

print docopt(__doc__)

私が実行した場合：

farmersmarket.py buy --item eggs --quantity 100 115 --price 0.25

The expected behaviour is to buy a random quantity of eggs between the values 100 and 115 at the price 0.25. This works without problems at least when it comes to interpreting the arguments. In other words docopt gets everything as intended:

{'--debug': False,
 '--help': False,
 '--item': True,
 '--price': True,
 '--quantity': True,
 '--version': False,
 '<item>': 'eggs',
 '<price>': '0.25',
 '<quantity>': ['100', '115'],
 'buy': True}

However sometimes I do not want to buy a random amount of eggs but a specific amount. In this case the --quantity option takes only one argument:

farmersmarket.py buy --item eggs --quantity 471 --price 0.25

But this fails as docopt interprets --price 0.25 as a repeating element of --quantity and loses the value of <price>:

{'--debug': False,
 '--help': False,
 '--item': True,
 '--price': True,
 '--quantity': True,
 '--version': False,
 '<item>': 'eggs',
 '<price>': None,
 '<quantity>': ['471', '0.25'],
 'buy': True}

How can I get other options to work after repeating elements?