--- asyncio/tasks.py	2016-06-13 16:25:53.000000000 +0200
+++ asyncio/tasks.py	2016-06-15 10:10:51.637567952 +0200
@@ -208,14 +208,22 @@
         terminates with a CancelledError exception (even if cancel()
         was not called).
         """
+        print('Entered Task.cancel() for task {}'.format(self))
         if self.done():
+            print('Task is done(), refusing to cancel')
             return False
         if self._fut_waiter is not None:
+            print('Task is not done() and we have a _fut_waiter: Cancelling fut_waiter {}'.format(self._fut_waiter))
             if self._fut_waiter.cancel():
+                print('Great, _fut_waiter has agreed to be cancelled. We can now also return True')
                 # Leave self._fut_waiter; it may be a Task that
                 # catches and ignores the cancellation so we may have
                 # to cancel it again later.
                 return True
+            else:
+                print('_fut_waiter refused to be cancelled, now we have to cancel ourselves in the next _step')
+        else:
+            print('No _fut_waiter! Now we have to cancel ourselves in the next step')
         # It must be the case that self._step is already scheduled.
         self._must_cancel = True
         return True
@@ -657,6 +665,7 @@
         results[i] = res
         nfinished += 1
         if nfinished == nchildren:
+            print('All children finished OK, setting _GatheringFuture results!')
             outer.set_result(results)
 
     for i, fut in enumerate(children):