Fix/optimize test_asyncore.test_quick_connect() (#1188)

Don't use addCleanup() in test_quick_connect() because it keeps the
Thread object alive and so @reap_threads fails on its timeout of 1
second. "./python -m test -v test_asyncore -m test_quick_connect"
now takes 185 ms, instead of 11 seconds.

Other minor changes:

* Use "with sock:" to close the socket instead of
  try/finally: sock.close()
* Use self.skipTest() in test_quick_connect() to remove one
  indentation level and notice user that the test is specific to
  AF_INET and AF_INET6

Lib/test/test_asyncore.py

@@ -755,7 +755,8 @@ class BaseTestAPI:
     def test_set_reuse_addr(self):
         if HAS_UNIX_SOCKETS and self.family == socket.AF_UNIX:
             self.skipTest("Not applicable to AF_UNIX sockets.")
-        sock = socket.socket(self.family)
+
+        with socket.socket(self.family) as sock:
             try:
                 sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
             except OSError:
@@ -771,34 +772,32 @@ class BaseTestAPI:
                 s.set_reuse_addr()
                 self.assertTrue(s.socket.getsockopt(socket.SOL_SOCKET,
                                                      socket.SO_REUSEADDR))
-        finally:
-            sock.close()
 
     @unittest.skipUnless(threading, 'Threading required for this test.')
     @support.reap_threads
     def test_quick_connect(self):
         # see: http://bugs.python.org/issue10340
-        if self.family in (socket.AF_INET, getattr(socket, "AF_INET6", object())):
+        if self.family not in (socket.AF_INET, getattr(socket, "AF_INET6", object())):
+            self.skipTest("test specific to AF_INET and AF_INET6")
+
         server = BaseServer(self.family, self.addr)
         t = threading.Thread(target=lambda: asyncore.loop(timeout=0.1,
-                                                              count=500))
+                                                          count=500), name="ident")
         t.start()
-            def cleanup():
-                t.join(timeout=TIMEOUT)
-                if t.is_alive():
-                    self.fail("join() timed out")
-            self.addCleanup(cleanup)
-
-            s = socket.socket(self.family, socket.SOCK_STREAM)
+        try:
+            with socket.socket(self.family, socket.SOCK_STREAM) as s:
                 s.settimeout(.2)
                 s.setsockopt(socket.SOL_SOCKET, socket.SO_LINGER,
                              struct.pack('ii', 1, 0))
+
                 try:
                     s.connect(server.address)
                 except OSError:
                     pass
         finally:
-                s.close()
+            t.join(timeout=TIMEOUT)
+            if t.is_alive():
+                self.fail("join() timed out")
 
 class TestAPI_UseIPv4Sockets(BaseTestAPI):
     family = socket.AF_INET