Replace useless version check with import from __future__

tests/test_sftp.py

@@ -23,6 +23,8 @@ a real actual sftp server is contacted, and a new folder is created there to
 do test file operations in (so no existing files will be harmed).
 """
 
+from __future__ import with_statement
+
 from binascii import hexlify
 import logging
 import os
@@ -192,10 +194,6 @@ class SFTPTest (unittest.TestCase):
         """
         verify that an opened file can be used as a context manager
         """
-        major, minor, micro, releaselevel, serial = sys.version_info
-        if (major, minor) <= (2, 5):
-            return
-
         try:
             with sftp.open(FOLDER + '/duck.txt', 'w') as f:
                 f.write(ARTICLE)