Kill Container Probably Won't Remove Child from Parent

AbstractContainerBuilderContainerBuilder.killContainer() has the following code:

        PicoContainer parent = container.getParent();
        if (parent != null && parent instanceof MutablePicoContainer) {
	    synchronized (parent) {
	          ((MutablePicoContainer) parent).removeChildContainer(container);
		}
        }

Only problem is we have a situation like this:

MutablePico parent = <blah>
MutablePico child = parent.makeChildContainer();

then containerBuilder.killContainer(child) will NOT remove the child from the parent (possibly resulting in a memory leak. because parent will be an ImmutablePicoContainer.

I'll be checking in a test case that demonstrates this shortly.