When upgrading the test data twice, don't bail out because of an existing backup

test/test262/testcfg.py

Index: test/test262/testcfg.py
diff --git a/test/test262/testcfg.py b/test/test262/testcfg.py
index 89f729d9a34a533d8c58e0d1bca40d9e0ad0bf19..d4a7f5684f021a9f5b83a8e228c2d8096b8becb5 100644
--- a/test/test262/testcfg.py
+++ b/test/test262/testcfg.py
@@ -28,6 +28,7 @@
 
 import hashlib
 import os
+import shutil
 import sys
 import tarfile
 import urllib
@@ -98,6 +99,8 @@ class Test262TestSuite(testsuite.TestSuite):
       print "Downloading test data from %s ..." % archive_url
       urllib.urlretrieve(archive_url, archive_name)
       if os.path.exists(directory_name):
+        if os.path.exists(directory_old_name):
+          shutil.rmtree(directory_old_name)
         os.rename(directory_name, directory_old_name)
     if not os.path.exists(directory_name):
       print "Extracting test262-%s.tar.bz2 ..." % revision