Remove six and python 2.7 full support

Six is in use to help us to keep support for python 2.7.
Since the ussuri cycle we decide to remove the python 2.7
support so we can go ahead and also remove six usage from
the python code.

Review process and help
-----------------------
Removing six introduce a lot of changes and an huge amount of modified files
To simplify reviews we decided to split changes into several patches to avoid
painful reviews and avoid mistakes.

To review this patch you can use the six documentation [1] to obtain help and
understand choices.

Additional informations
-----------------------
Changes related to 'six.b(data)' [2]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

six.b [2] encode the given datas in latin-1 in python3 so I did the same
things in this patch.

Latin-1 is equal to iso-8859-1 [3].

This encoding is the default encoding [4] of certain descriptive HTTP
headers.

I suggest to keep latin-1 for the moment and to move to another encoding
in a follow-up patch if needed to move to most powerful encoding (utf8).

HTML4 support utf8 charset and utf8 is the default charset for HTML5 [5].

Note that this commit message is autogenerated and not necesserly contains
changes related to 'six.b'

[1] https://six.readthedocs.io/
[2] https://six.readthedocs.io/#six.b
[3] https://docs.python.org/3/library/codecs.html#standard-encodings
[4] https://www.w3schools.com/charsets/ref_html_8859.asp
[5] https://www.w3schools.com/html/html_charset.asp

Patch 26 of a serie of 28 patches

Change-Id: I861e30278e66b680cd64ef659ff889414d4e55fb

1 files changed, 2 insertions, 3 deletions

diff --git a/heat/tests/test_nested_stack.py b/heat/tests/test_nested_stack.py
index a4aa37bae..bd4f005d8 100644
--- a/heat/tests/test_nested_stack.py
+++ b/heat/tests/test_nested_stack.py
@@ -15,7 +15,6 @@
 import mock
 from oslo_config import cfg
 from requests import exceptions
-import six
 import yaml
 
 from heat.common import exception
@@ -164,7 +163,7 @@ Resources:
 
         res = self.assertRaises(exception.StackValidationFailed,
                                 stack.validate)
-        self.assertIn('Recursion depth exceeds', six.text_type(res))
+        self.assertIn('Recursion depth exceeds', str(res))
 
         calls = [mock.call('https://server.test/depth1.template'),
                  mock.call('https://server.test/depth2.template'),
@@ -229,7 +228,7 @@ Resources:
         tr.return_value = 2
         res = self.assertRaises(exception.StackValidationFailed,
                                 stack.validate)
-        self.assertIn('Recursion depth exceeds', six.text_type(res))
+        self.assertIn('Recursion depth exceeds', str(res))
         expected_count = cfg.CONF.get('max_nested_stack_depth') + 1
         self.assertEqual(expected_count, urlfetch.get.call_count)