Unexpected repeated arguments when using repeated option.

[rgrannell1]

Docopt seems to erroneously repeat arguments when parsing an option block when:

• it is a repeating option.
• it has multiple matching options in the same '[ ]' block.

Environment:

• NodeJS: 5.7.0
• Docopt: 0.6.2

Test Cases:

const doc = `
Usage:
    foobar [-f X ... | --foo X ...]
Options:
    -f X, --foo X     bar

`
console.log(require('docopt').docopt(doc))

const doc = `
Usage:
    foobar [-f X ...] [--foo X ...]
Options:
    -f X, --foo X    bar.

`
console.log(require('docopt').docopt(doc))

Tests:

:-1:

<test case 1> -f 1 -f 2 -f 3 -f 4 -f 5 -f 6
{ '--foo': [ '1', '2', '3', '4', '5', '6', '2', '3', '4', '5', '6' ] }

:+1:

<test case 2> -f 1 -f 2 -f 3 -f 4 -f 5 -f 6
{ '--foo': [ '1', '2', '3', '4', '5', '6' ] }