Errors in "client" methods in test_socket were ignored because of a bogus except clause.

(this could reveal test failures!)

Lib/test/test_socket.py

@@ -2,6 +2,7 @@
 
 import unittest
 from test import support
+from unittest.case import _ExpectedFailure
 
 import errno
 import io
@@ -241,7 +242,7 @@ class ThreadableTest:
             raise TypeError("test_func must be a callable function")
         try:
             test_func()
-        except unittest._ExpectedFailure:
+        except _ExpectedFailure:
             # We deliberately ignore expected failures
             pass
         except BaseException as e: