Fix incorrect ZPL version in file headers

src/zope/testbrowser/tests.py

@@ -4,7 +4,7 @@
 # All Rights Reserved.
 #
 # This software is subject to the provisions of the Zope Public License,
-# Version 2.0 (ZPL).  A copy of the ZPL should accompany this distribution.
+# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
 # THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
 # WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 # WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
@@ -26,7 +26,6 @@
 import socket
 import sys
 import unittest
-import unittest
 import urllib2
 import zope.app.testing.functional
 import zope.testbrowser.browser