Convert import try/except to use test_support.import_module().

Lib/test/test_fork1.py

@@ -3,14 +3,11 @@
 
 import os
 import time
-import unittest
 from test.fork_wait import ForkWait
-from test.test_support import run_unittest, reap_children
+from test.test_support import run_unittest, reap_children, import_module
+
+import_module('os.fork')
 
-try:
-    os.fork
-except AttributeError:
-    raise unittest.SkipTest, "os.fork not defined -- skipping test_fork1"
 
 class ForkTest(ForkWait):
     def wait_impl(self, cpid):