Fix test incompatibility with PyPy3

MANIFEST.in

@@ -1,2 +1,2 @@
 include *.py *.txt *.rst *.md *.ini MANIFEST.in
-recursive-include test docs *.rst *.py make.bat Makefile
+recursive-include dev test docs *.rst *.py make.bat Makefile

test/test_contextlib.py

@@ -9,6 +9,7 @@ from contextlib2 import *  # Tests __all__
 from test import support
 from test.support import os_helper
 import weakref
+import gc
 
 
 class TestAbstractContextManager(unittest.TestCase):
@@ -228,6 +229,8 @@ def woohoo():
         def woohoo(a, b):
             a = weakref.ref(a)
             b = weakref.ref(b)
+            # Allow test to work with a non-refcounted GC
+            gc.collect(); gc.collect(); gc.collect()
             self.assertIsNone(a())
             self.assertIsNone(b())
             yield

test/test_contextlib_async.py

@@ -1,7 +1,7 @@
 import asyncio
 from contextlib2 import (
     asynccontextmanager, AbstractAsyncContextManager,
-    AsyncExitStack, nullcontext, aclosing)
+    AsyncExitStack, nullcontext, aclosing, contextmanager)
 import functools
 from test import support
 import unittest
@@ -346,14 +346,17 @@ class AclosingTestCase(unittest.TestCase):
     async def test_aclosing_bpo41229(self):
         state = []
 
-        class Resource:
-            def __del__(self):
+        @contextmanager
+        def sync_resource():
+            try:
+                yield
+            finally:
                 state.append(1)
 
         async def agenfunc():
-            r = Resource()
-            yield -1
-            yield -2
+            with sync_resource():
+                yield -1
+                yield -2
 
         x = agenfunc()
         self.assertEqual(state, [])