Null pointer exception in Rail.makeVar[boolean]()

public class Bug {

    public static def main(args:Rail[String]):void {
        val x = Rail.makeVar[boolean](10);
    }
}

Exception in thread "pool-0-thread-0: Main Activity" java.lang.NullPointerException
at x10.types.BooleanType.setArray(BooleanType.java:37)
at x10.types.BooleanType.setArray(BooleanType.java:15)
at x10.core.Rail.set(Rail.java:25)
at x10.core.RailFactory.makeVarRail(RailFactory.java:48)
at Bug.main(Bug.java:66)
at Bug$Main.runX10Task(Bug.java:39)
at x10.runtime.InvocationStrategy$AsyncInFinishStrategy.invokeX10Task(InvocationStrategy.java:80)
at x10.runtime.Activity.run(Activity.java:193)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:665)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:690)
at java.lang.Thread.run(Thread.java:797)

Workaround: specify explicit initializer (nat)=>false