Fix Slow Non-deterministic Test

Somehow I missed the Thread.sleep to force the scenario so most of the time this test would run very slow (or forever).
I'm surprised the unit tests passed before... just random luck on thread scheduling.

Author: benjchristensen

src/test/java/rx/internal/operators/OperatorObserveOnTest.java

@@ -687,7 +687,7 @@ public void testErrorPropagatesWhenNoOutstandingRequests() {
 
                     @Override
                     public void call(Notification<? super Long> n) {
-                        //                        System.out.println("BEFORE " + n);
+                        //                                                System.out.println("BEFORE " + n);
                     }
 
                 })
@@ -696,7 +696,11 @@ public void call(Notification<? super Long> n) {
 
                     @Override
                     public void call(Notification<? super Long> n) {
-                        //                        System.out.println("AFTER " + n);
+                        try {
+                            Thread.sleep(100);
+                        } catch (InterruptedException e) {
+                        }
+                        //                                                System.out.println("AFTER " + n);
                     }
 
                 });