make this test work when run repeatedly.
diff --git a/Lib/test/test_dircache.py b/Lib/test/test_dircache.py
index 52014e2..3f10872 100644
--- a/Lib/test/test_dircache.py
+++ b/Lib/test/test_dircache.py
@@ -5,13 +5,12 @@
 
 import unittest
 from test.test_support import run_unittest, TESTFN
-import dircache, os, time, sys
+import dircache, os, time, sys, tempfile
 
 
 class DircacheTests(unittest.TestCase):
     def setUp(self):
-        self.tempdir = TESTFN+"_dir"
-        os.mkdir(self.tempdir)
+        self.tempdir = tempfile.mkdtemp()
 
     def tearDown(self):
         for fname in os.listdir(self.tempdir):