Fix test262 harness to purge old data directory.

test/test262/testcfg.py

Index: test/test262/testcfg.py
diff --git a/test/test262/testcfg.py b/test/test262/testcfg.py
index fc03c4d02e56f833487506be9f3c8a18a719ce0a..2c9bf06f1428741a935406c769bf085f16f5a21c 100644
--- a/test/test262/testcfg.py
+++ b/test/test262/testcfg.py
@@ -104,9 +104,12 @@ class Test262TestConfiguration(test.TestConfiguration):
     archive_url = TEST_262_URL % revision
     archive_name = join(self.root, 'test262-%s.tar.bz2' % revision)
     directory_name = join(self.root, 'data')
+    directory_old_name = join(self.root, 'data.old')
     if not exists(archive_name):
       print "Downloading test data from %s ..." % archive_url
       urllib.urlretrieve(archive_url, archive_name)
+      if exists(directory_name):
+        os.rename(directory_name, directory_old_name)
     if not exists(directory_name):
       print "Extracting test262-%s.tar.bz2 ..." % revision
       md5 = hashlib.md5()