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);	}
}