empty values aren't stored

[kbknapp]

extern crate clap;

use clap::{App, AppSettings};

fn main() {
    let m = App::new("test")
        .setting(AppSettings::TrailingVarArg)
        .arg_from_usage("<command>... 'some feature'")
        .get_matches();

    for c in m.values_of("command").unwrap() {
        println!("{}", c);
    }

    println!("len: {}", m.values_of("command").unwrap().collect::<Vec<_>>().len());

}

Running with

$ test ""
len: 0