Replace six.iteritems() with .items()

1. As mentioned in [1], we should avoid using six.iteritems to achieve
   iterators. We can use dict.items instead, as it will return iterators
   in PY3 as well. And dict.items/keys will more readable.

2. In py2, the performance about list should be negligible,
   see the link [2].

[1] https://wiki.openstack.org/wiki/Python3
[2] http://lists.openstack.org/pipermail/openstack-dev/2015-June/066391.html

Co-Authored-By: Akihiro Motoki <amotoki@gmail.com>
Change-Id: I4b9edb326444264c0f6c4ad281acaac356a07e85
Implements: blueprint replace-iteritems-with-items

openstackclient/api/object_store_v1.py

@@ -19,7 +19,6 @@ import os
 import sys
 
 from osc_lib import utils
-import six
 from six.moves import urllib
 
 from openstackclient.api import api
@@ -559,7 +558,7 @@ class APIv1(api.BaseAPI):
         log = logging.getLogger(__name__ + '._set_properties')
 
         headers = {}
-        for k, v in six.iteritems(properties):
+        for k, v in properties.items():
             if not utils.is_ascii(k) or not utils.is_ascii(v):
                 log.error('Cannot set property %s to non-ascii value', k)
                 continue
@@ -572,7 +571,7 @@ class APIv1(api.BaseAPI):
         # Add in properties as a top level key, this is consistent with other
         # OSC commands
         properties = {}
-        for k, v in six.iteritems(headers):
+        for k, v in headers.items():
             if k.lower().startswith(header_tag):
                 properties[k[len(header_tag):]] = v
         return properties