Issue #4397. Fix occasional test_socket failure on OS X.

Lib/test/test_socket.py

@@ -584,6 +584,10 @@ class BasicTCPTest(SocketConnectedTest):
         # Testing shutdown()
         msg = self.cli_conn.recv(1024)
         self.assertEqual(msg, MSG)
+        # wait for _testShutdown to finish: on OS X, when the server
+        # closes the connection the client also becomes disconnected,
+        # and the client's shutdown call will fail. (Issue #4937.)
+        self.done.wait()
 
     def _testShutdown(self):
         self.serv_conn.send(MSG)

Misc/NEWS

@@ -357,6 +357,8 @@ C-API
 Extension Modules
 -----------------
 
+- Issue #4937: Fix occasional test_socket failure on OS X.
+
 - Issue #4279: Fix build of parsermodule under Cygwin.
 
 - Issue #4051: Prevent conflict of UNICODE macros in cPickle.