Actually have test_largefile execute. Call to test.test_support.run_unittest()
somehow got lost.
diff --git a/Lib/test/test_largefile.py b/Lib/test/test_largefile.py
index f7697d2..8157ddb 100644
--- a/Lib/test/test_largefile.py
+++ b/Lib/test/test_largefile.py
@@ -171,6 +171,10 @@
     f = open(TESTFN, 'w')
     if hasattr(f, 'truncate'):
         suite.addTest(TestCase('test_truncate'))
+    f.close()
+    unlink(TESTFN)
+    run_unittest(suite)
+    unlink(TESTFN)
 
 if __name__ == '__main__':
     main_test()