fs::create_dir_all fails if root dir does not exist

[oakes]

The following panics:

use std::fs;

fn main() {
    fs::create_dir_all("a/b/c").unwrap();
}

The following works:

use std::fs;

fn main() {
    fs::create_dir("a").unwrap();
    fs::create_dir_all("a/b/c").unwrap();
}

Apologies in advance if this is intended behavior.

[mvdnes]

I have found that it also works when using:

use std::fs;

fn main() {
    fs::create_dir_all("./a/b/c").unwrap();
}

[alexcrichton]

This will be fixed by #23383