Stackless issue #251: Fix test case broken by upstream

Upstream fix for bpo-39386 broke Stackless test case
test_pickle.TestAsyncGenPickling.

(cherry picked from commit c3f61b0)

Author: Anselm Kruis

Stackless/unittests/test_pickle.py

@@ -803,7 +803,7 @@ def test_without_pickling(self):
         c = ag.__anext__()
         self.assertRaises(StopAsyncIteration, c.send, None)
         self.assertIsNone(ag.ag_frame)
-        self.assertRaises(StopIteration, c.send, None)
+        self.assertRaisesRegex(RuntimeError, "cannot reuse already awaited", c.send, None)
         c = ag.__anext__()
         self.assertRaises(StopAsyncIteration, c.send, None)
 
@@ -822,7 +822,7 @@ def test_pickling1(self):
         c = ag.__anext__()
         self.assertRaises(StopAsyncIteration, c.send, None)
         self.assertIsNone(ag.ag_frame)
-        self.assertRaises(StopIteration, c.send, None)
+        self.assertRaisesRegex(RuntimeError, "cannot reuse already awaited", c.send, None)
         c = ag.__anext__()
         self.assertRaises(StopAsyncIteration, c.send, None)
 
@@ -844,7 +844,7 @@ def test_pickling2(self):
             c = ag.__anext__()
             self.assertRaises(StopAsyncIteration, c.send, None)
             self.assertIsNone(ag.ag_frame)
-            self.assertRaises(StopIteration, c.send, None)
+            self.assertRaisesRegex(RuntimeError, "cannot reuse already awaited", c.send, None)
             c = ag.__anext__()
             self.assertRaises(StopAsyncIteration, c.send, None)
             ag = self.loads(p)
@@ -869,7 +869,7 @@ def test_pickling3(self):
         p = self.dumps(ag)
         ag = self.loads(p)
         self.assertIsNone(ag.ag_frame)
-        self.assertRaises(StopIteration, c.send, None)
+        self.assertRaisesRegex(RuntimeError, "cannot reuse already awaited", c.send, None)
         c = ag.__anext__()
         self.assertRaises(StopAsyncIteration, c.send, None)