Rust: cannot use `package: true` and `-- --nocapture` like params

[gbataille]

If I'm not mistaken, it's impossible to have both the package: true option and use an args list that contains --

I think this is because the package args are injected after the args

I'm willing to do a proposed implementation as part of https://github.com/klen/nvim-test/pull/23 if you want