Update cfg from openstack-common

Use openstack-common's update.py script to pull in some recent changes:

 * Add the Mapping interface to cfg.ConfigOpts
 * Add support to cfg for disabling interspersed args

Make use of both of these in nova/flags.py.

Add some dire warnings to HACKING about directly modifying the copy of
openstack-common code. I'm confident they won't be ignored :-)

Change-Id: I7ef75d18922c0bbb8844453b48cad0418034bc11

HACKING.rst

@@ -179,3 +179,18 @@ without the patch and passes with the patch.
 
 For more information on creating unit tests and utilizing the testing
 infrastructure in OpenStack Nova, please read nova/testing/README.rst.
+
+
+openstack-common
+----------------
+
+A number of modules from openstack-common are imported into the project.
+
+These modules are "incubating" in openstack-common and are kept in sync
+with the help of openstack-common's update.py script. See:
+
+  http://wiki.openstack.org/CommonLibrary#Incubation
+
+The copy of the code should never be directly modified here. Please
+always update openstack-common first and then run the script to copy
+the changes across.

nova/flags.py

@@ -69,7 +69,7 @@ class FlagValues(object):
 
     def __init__(self):
         self._conf = cfg.ConfigOpts()
-        self._conf._oparser.disable_interspersed_args()
+        self._conf.disable_interspersed_args()
         self._opts = {}
         self.Reset()
 
@@ -128,7 +128,7 @@ class FlagValues(object):
         self._conf.set_default(name, default)
 
     def __iter__(self):
-        return self.FlagValuesDict().iterkeys()
+        return self._conf.iterkeys()
 
     def __getitem__(self, name):
         self._parse()
@@ -147,12 +147,12 @@ class FlagValues(object):
     def FlagValuesDict(self):
         self._parse()
         ret = {}
-        for opt in self._opts.values():
-            ret[opt.dest] = getattr(self, opt.dest)
+        for name in self._conf:
+            ret[name] = getattr(self, name)
         return ret
 
     def add_option(self, opt):
-        if opt.dest in self._opts:
+        if opt.dest in self._conf:
             return
 
         self._opts[opt.dest] = opt