A partial build (`satis build satis.json web/ vendor/package`) narrows the
repository list down to the ones providing the requested packages. The
dependency pass then reused that narrowed list, so with
`require-dependencies` nothing the filtered package required could be
found -- packagist.org and every other repository had already been
dropped. Feed the dependency repository set the repositories the filter
removed, the same way the repository-URL filter already does.
Fixes#706
dualfroz