add check for output attr

Author: anikamukherji

src/future/tests/base.py

@@ -342,6 +342,9 @@ def _futurize_test_script(self, filename='mytestscript.py', stages=(1, 2),
                         '----\n%s\n----' % f.read(),
                     )
             ErrorClass = (FuturizeError if 'futurize' in script else PasteurizeError)
+            if not hasattr(e, 'output'):
+                # The attribute CalledProcessError.output doesn't exist on Py2.6
+                e.output = None
             raise ErrorClass(msg, e.returncode, e.cmd, output=e.output)
         return output