Reflect Python 3.4.4 asyncio.queues changes in stubs (#847)

Fixes #846

stdlib/3.4/asyncio/__init__.pyi

@@ -72,7 +72,6 @@ from asyncio.queues import (
     Queue as Queue,
     PriorityQueue as PriorityQueue,
     LifoQueue as LifoQueue,
-    JoinableQueue as JoinableQueue,
     QueueFull as QueueFull,
     QueueEmpty as QueueEmpty,
 )
@@ -84,6 +83,9 @@ from asyncio.locks import (
     BoundedSemaphore as BoundedSemaphore,
 )
 
+if sys.version_info < (3, 5):
+    from asyncio.queues import JoinableQueue as JoinableQueue
+
 # TODO: It should be possible to instantiate these classes, but mypy
 # currently disallows this.
 # See https://github.com/python/mypy/issues/1843

stdlib/3.4/asyncio/queues.pyi

@@ -1,3 +1,4 @@
+import sys
 from asyncio.events import AbstractEventLoop
 from .coroutines import coroutine
 from .futures import Future
@@ -32,6 +33,10 @@ class Queue(Generic[T]):
     @coroutine
     def get(self) -> Future[T]: ...
     def get_nowait(self) -> T: ...
+    if sys.version_info >= (3, 4):
+        @coroutine
+        def join(self) -> None: ...
+        def task_done(self) -> None: ...
 
 
 class PriorityQueue(Queue): ...
@@ -39,8 +44,8 @@ class PriorityQueue(Queue): ...
 
 class LifoQueue(Queue): ...
 
-
-class JoinableQueue(Queue):
-    def task_done(self) -> None: ...
-    @coroutine
-    def join(self) -> None: ...
+if sys.version_info < (3, 5):
+    class JoinableQueue(Queue):
+        def task_done(self) -> None: ...
+        @coroutine
+        def join(self) -> None: ...