replace has problems with empty strings

[fulara]

Seems like a replace has problems processing empty strings. example:

extern crate regex;
use regex::Regex;
fn main() {
    let regex = Regex::new("\\d*").unwrap();
    let s = regex.replace("", "replaced").into_owned();
    assert_eq!("replaced", s);
}

That fails. however:

extern crate regex;
use regex::Regex;
fn main() {
    let regex = Regex::new("\\d*").unwrap();
    let s = regex.find("");
    assert!(s.is_some());
}

That one passes.
Thanks to lapinot I've workaround here:

extern crate regex;
use regex::Regex;
fn main() {
    let regex = Regex::new("\\d*").unwrap();
    let s = regex.replace("", |caps: &regex::Captures| { "replaced".to_string() }).into_owned();
    assert_eq!("replaced", s);
}

[BurntSushi]

This is probably a dupe of #393, but we can leave this open until a fix confirms.

[BurntSushi]

Fixed by #395