Resolve doesn't report name conflicts between a module renaming and another module

[catamorphism]

Test:

extern mod std;

use list = std::map::chained;
use std::list;

fn main() {
    let _x: list::T<int, int> = list::mk();
}

This program should get rejected because I've aliased list to another module, but I'm also using std::list, so list is ambiguous. But the type error I actually get is about list::mk not being resolved (which is to say, std::list::mk not being resolved). The failure should happen earlier.

[graydon]

use declarations shadow one another; this is working as intended.