Can't export an imported type in a .rs file referred to by a .rc

[pcwalton]

export.rc:
meta(name="export");
mod exportimpl;

exportimpl.rs:
import a.t;
export t;
mod a {
export t;
type t = int;
}

And when I compile:
$ rustboot -shared export.rc
Fatal error: exception Not_found

[pcwalton]

Compiling the .rs by itself succeeds, oddly enough!

[graydon]

WONTFIX (not required for bootstrapping; all this logic is new in rustc)