replace dict.iteritems() with six.iteritems(dict)

According to https://wiki.openstack.org/wiki/Python3 dict.iteritems()
should be replaced with six.iteritems(dict).

Added six >= 1.6.0 as new requirement. Removed six from test requirements.

Change-Id: Ifba282b1bde9681268e6e46ffd024c96c6b9be05

requirements.txt

@@ -18,3 +18,4 @@ python-swiftclient>=1.6
 python-keystoneclient>=0.4.2
 PrettyTable>=0.6,<0.8
 babel
+six>=1.6.0

test-requirements.txt

@@ -7,7 +7,6 @@ docutils==0.9.1
 discover
 fixtures>=0.3.14
 python-subunit
-six>=1.4.1
 testrepository>=0.0.17
 testtools>=0.9.32
 sphinxcontrib-programoutput

zuul/lib/swift.py

@@ -17,6 +17,7 @@ from hashlib import sha1
 from time import time
 import os
 import random
+import six
 import string
 import swiftclient
 import urlparse
@@ -116,7 +117,7 @@ class Swift(object):
             'file_path_prefix': ''
         }
 
-        for key, default in settings.iteritems():
+        for key, default in six.iteritems(settings):
             if key in kwargs:
                 settings[key] = kwargs[key]
             elif self.config.has_option('swift', 'default_' + key):

zuul/rpclistener.py

@@ -19,6 +19,7 @@ import threading
 import traceback
 
 import gear
+import six
 
 import model
 
@@ -129,7 +130,8 @@ class RPCListener(object):
         # args = json.loads(job.arguments)
         # TODO: use args to filter by pipeline etc
         running_items = []
-        for pipeline_name, pipeline in self.sched.layout.pipelines.iteritems():
+        for pipeline_name, pipeline in six.iteritems(
+                self.sched.layout.pipelines):
             for queue in pipeline.queues:
                 for item in queue.queue:
                     running_items.append(item.formatJSON())