Sade parses past `--`

[benmerckx]

If an optional argument is defined sade will parse after --

import sade from 'sade'
sade('prog')
  .command('build [config]').action(console.log)
  .parse(['node', 'cli.js', 'build', '--', 'abc', 'xyz'])

Results in "abc", {_: ["xyz"]}

But I'd expect it to parse undefined, {_: ["abc', "xyz"]}