assert or execption case program hang in multi thread

[liyu]

code as below, assert can't terminate the program when main thread is 
running, is it a bug or i miss something?

import tango.core.Thread;
void test()
{
        while(1) {
                assert(false);
                //throw new Exception("test");
        }
}
void main() {
        auto thread = new Thread(&test);
        thread.start();

       //if i remove the 3 lines below, then every thing work as expected
        while(1) {
                Thread.sleep(100);      }
}