use boolean flag for completion in FuncWithErrors because o.onError and o.onCompleted may be buffered in o so that unsubscription is delayed

Author: davidmoten

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

@@ -397,6 +397,8 @@ public void call(final Subscriber<? super String> o) {
                 final AtomicLong req = new AtomicLong();
                 // 0 = not set, 1 = fast path, 2 = backpressure
                 final AtomicInteger path = new AtomicInteger(0);
+                volatile boolean done = false;
+                
                 @Override
                 public void request(long n) {
                     if (n == Long.MAX_VALUE && path.compareAndSet(0, 1)) {
@@ -410,11 +412,12 @@ public void request(long n) {
                         }
                         return;
                     }
-                    if (n > 0 && req.getAndAdd(n) == 0 && (path.get() == 2 || path.compareAndSet(0, 2)) && !o.isUnsubscribed()) {
+                    if (n > 0 && req.getAndAdd(n) == 0 && (path.get() == 2 || path.compareAndSet(0, 2)) && !done) {
                         int i = count.getAndIncrement();
                         if (i < numFailures) {
                             o.onNext("beginningEveryTime");
                             o.onError(new RuntimeException("forced failure: " + (i + 1)));
+                            done = true;
                         } else {
                             do {
                                 if (i == numFailures) {
@@ -423,6 +426,7 @@ public void request(long n) {
                                 if (i > numFailures) {
                                     o.onNext("onSuccessOnly");
                                     o.onCompleted();
+                                    done = true;
                                     break;
                                 }
                                 i = count.getAndIncrement();