Ignore Python 2 specific code in tests

test/test_prefix.py

@@ -1,9 +1,4 @@
-try:
-    from itertools import zip_longest
-except ImportError:
-    # Python 2
-    from itertools import izip_longest as zip_longest
-
+from itertools import zip_longest
 from codecs import BOM_UTF8
 
 import pytest