Add min version of six

Author: srinivasreddy

_pytest/assertion/__init__.py

@@ -2,8 +2,8 @@
 support for presenting detailed information in failing assertions.
 """
 from __future__ import absolute_import, division, print_function
-import py
 import sys
+import six
 
 from _pytest.assertion import util
 from _pytest.assertion import rewrite
@@ -126,7 +126,7 @@ def callbinrepr(op, left, right):
             if new_expl:
                 new_expl = truncate.truncate_if_required(new_expl, item)
                 new_expl = [line.replace("\n", "\\n") for line in new_expl]
-                res = py.builtin._totext("\n~").join(new_expl)
+                res = six.text_type("\n~").join(new_expl)
                 if item.config.getvalue("assertmode") == "rewrite":
                     res = res.replace("%", "%%")
                 return res

setup.py

@@ -43,7 +43,7 @@ def has_environment_marker_support():
 
 
 def main():
-    install_requires = ['py>=1.4.33', 'six','setuptools']  # pluggy is vendored in _pytest.vendored_packages
+    install_requires = ['py>=1.4.33', 'six>=1.10.0','setuptools']  # pluggy is vendored in _pytest.vendored_packages
     extras_require = {}
     if has_environment_marker_support():
         extras_require[':python_version=="2.6"'] = ['argparse']