diff --git a/quantum/openstack/common/cfg.py b/quantum/openstack/common/cfg.py
index abd191c168..bcd1f05fdf 100644
--- a/quantum/openstack/common/cfg.py
+++ b/quantum/openstack/common/cfg.py
@@ -367,6 +367,11 @@ class ConfigFileValueError(Error):
     pass
 
 
+def _fixpath(p):
+    """Apply tilde expansion and absolutization to a path."""
+    return os.path.abspath(os.path.expanduser(p))
+
+
 def _get_config_dirs(project=None):
     """Return a list of directors where config files may be located.
 
@@ -384,11 +389,9 @@ def _get_config_dirs(project=None):
       ~/
       /etc/
     """
-    fix_path = lambda p: os.path.abspath(os.path.expanduser(p))
-
     cfg_dirs = [
-        fix_path(os.path.join('~', '.' + project)) if project else None,
-        fix_path('~'),
+        _fixpath(os.path.join('~', '.' + project)) if project else None,
+        _fixpath('~'),
         os.path.join('/etc', project) if project else None,
         '/etc'
     ]
@@ -809,7 +812,7 @@ class OptGroup(object):
         if _is_opt_registered(self._opts, opt):
             return False
 
-        self._opts[opt.dest] = {'opt': opt, 'override': None, 'default': None}
+        self._opts[opt.dest] = {'opt': opt}
 
         return True
 
@@ -1087,7 +1090,7 @@ class ConfigOpts(collections.Mapping):
         if _is_opt_registered(self._opts, opt):
             return False
 
-        self._opts[opt.dest] = {'opt': opt, 'override': None, 'default': None}
+        self._opts[opt.dest] = {'opt': opt}
 
         return True
 
@@ -1205,6 +1208,33 @@ class ConfigOpts(collections.Mapping):
         opt_info = self._get_opt_info(name, group)
         opt_info['default'] = default
 
+    @__clear_cache
+    def clear_override(self, name, group=None):
+        """Clear an override an opt value.
+
+        Clear a previously set override of the command line, config file
+        and default values of a given option.
+
+        :param name: the name/dest of the opt
+        :param group: an option OptGroup object or group name
+        :raises: NoSuchOptError, NoSuchGroupError
+        """
+        opt_info = self._get_opt_info(name, group)
+        opt_info.pop('override', None)
+
+    @__clear_cache
+    def clear_default(self, name, group=None):
+        """Clear an override an opt's default value.
+
+        Clear a previously set override of the default value of given option.
+
+        :param name: the name/dest of the opt
+        :param group: an option OptGroup object or group name
+        :raises: NoSuchOptError, NoSuchGroupError
+        """
+        opt_info = self._get_opt_info(name, group)
+        opt_info.pop('default', None)
+
     def _all_opt_infos(self):
         """A generator function for iteration opt infos."""
         for info in self._opts.values():
@@ -1221,8 +1251,8 @@ class ConfigOpts(collections.Mapping):
     def _unset_defaults_and_overrides(self):
         """Unset any default or override on all options."""
         for info, group in self._all_opt_infos():
-            info['default'] = None
-            info['override'] = None
+            info.pop('default', None)
+            info.pop('override', None)
 
     def disable_interspersed_args(self):
         """Set parsing to stop on the first non-option.
@@ -1268,10 +1298,10 @@ class ConfigOpts(collections.Mapping):
         """
         dirs = []
         if self.config_dir:
-            dirs.append(self.config_dir)
+            dirs.append(_fixpath(self.config_dir))
 
         for cf in reversed(self.config_file):
-            dirs.append(os.path.dirname(cf))
+            dirs.append(os.path.dirname(_fixpath(cf)))
 
         dirs.extend(_get_config_dirs(self.project))
 
@@ -1345,10 +1375,10 @@ class ConfigOpts(collections.Mapping):
             return self.GroupAttr(self, self._get_group(name))
 
         info = self._get_opt_info(name, group)
-        default, opt, override = [info[k] for k in sorted(info.keys())]
+        opt = info['opt']
 
-        if override is not None:
-            return override
+        if 'override' in info:
+            return info['override']
 
         values = []
         if self._cparser is not None:
@@ -1376,8 +1406,8 @@ class ConfigOpts(collections.Mapping):
         if values:
             return values
 
-        if default is not None:
-            return default
+        if 'default' in info:
+            return info['default']
 
         return opt.default
 
@@ -1452,6 +1482,8 @@ class ConfigOpts(collections.Mapping):
             config_dir_glob = os.path.join(self.config_dir, '*.conf')
             config_files += sorted(glob.glob(config_dir_glob))
 
+        config_files = [_fixpath(p) for p in config_files]
+
         self._cparser = MultiConfigParser()
 
         try:
@@ -1469,10 +1501,10 @@ class ConfigOpts(collections.Mapping):
         :raises: RequiredOptError
         """
         for info, group in self._all_opt_infos():
-            default, opt, override = [info[k] for k in sorted(info.keys())]
+            opt = info['opt']
 
             if opt.required:
-                if (default is not None or override is not None):
+                if ('default' in info or 'override' in info):
                     continue
 
                 if self._get(opt.name, group) is None:
diff --git a/quantum/openstack/common/excutils.py b/quantum/openstack/common/excutils.py
index 67c9fa9511..5dd4830176 100644
--- a/quantum/openstack/common/excutils.py
+++ b/quantum/openstack/common/excutils.py
@@ -30,14 +30,14 @@ def save_and_reraise_exception():
     """Save current exception, run some code and then re-raise.
 
     In some cases the exception context can be cleared, resulting in None
-    being attempted to be reraised after an exception handler is run. This
+    being attempted to be re-raised after an exception handler is run. This
     can happen when eventlet switches greenthreads or when running an
     exception handler, code raises and catches an exception. In both
     cases the exception context will be cleared.
 
     To work around this, we save the exception state, run handler code, and
     then re-raise the original exception. If another exception occurs, the
-    saved exception is logged and the new exception is reraised.
+    saved exception is logged and the new exception is re-raised.
     """
     type_, value, tb = sys.exc_info()
     try:
diff --git a/quantum/openstack/common/importutils.py b/quantum/openstack/common/importutils.py
index 2fbb0291a0..f45372b4db 100644
--- a/quantum/openstack/common/importutils.py
+++ b/quantum/openstack/common/importutils.py
@@ -29,7 +29,7 @@ def import_class(import_str):
     try:
         __import__(mod_str)
         return getattr(sys.modules[mod_str], class_str)
-    except (ImportError, ValueError, AttributeError), exc:
+    except (ValueError, AttributeError), exc:
         raise ImportError('Class %s cannot be found (%s)' %
                           (class_str,
                            traceback.format_exception(*sys.exc_info())))
diff --git a/quantum/openstack/common/notifier/api.py b/quantum/openstack/common/notifier/api.py
index 36934062c0..38fbde049d 100644
--- a/quantum/openstack/common/notifier/api.py
+++ b/quantum/openstack/common/notifier/api.py
@@ -13,7 +13,6 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import inspect
 import uuid
 
 from quantum.openstack.common import cfg
@@ -140,9 +139,8 @@ def notify(context, publisher_id, event_type, priority, payload):
             driver.notify(context, msg)
         except Exception, e:
             LOG.exception(_("Problem '%(e)s' attempting to "
-                            "send to notification system. "
-                            "Payload=%(payload)s") %
-                          locals())
+              "send to notification system. Payload=%(payload)s") %
+                            locals())
 
 
 _drivers = None
@@ -171,7 +169,7 @@ def add_driver(notification_driver):
         except ImportError as e:
             LOG.exception(_("Failed to load notifier %s. "
                             "These notifications will not be sent.") %
-                          notification_driver)
+                            notification_driver)
     else:
         # Driver is already loaded; just add the object.
         _drivers[notification_driver] = notification_driver
diff --git a/quantum/openstack/common/policy.py b/quantum/openstack/common/policy.py
index 3eb5c526c6..d71458c804 100644
--- a/quantum/openstack/common/policy.py
+++ b/quantum/openstack/common/policy.py
@@ -173,7 +173,7 @@ class Brain(object):
             LOG.warning(_("Inheritance-based rules are deprecated; update "
                           "_check_%s") % match_kind)
             func = (lambda brain, kind, value, target, cred:
-                    old_func(value, target, cred))
+                        old_func(value, target, cred))
 
         if not func:
             LOG.error(_("No handler for matches of kind %s") % match_kind)
@@ -296,5 +296,5 @@ def _check_generic(brain, match_kind, match, target_dict, cred_dict):
     # TODO(termie): do dict inspection via dot syntax
     match = match % target_dict
     if match_kind in cred_dict:
-        return match == cred_dict[match_kind]
+        return match == unicode(cred_dict[match_kind])
     return False
diff --git a/quantum/openstack/common/rpc/common.py b/quantum/openstack/common/rpc/common.py
index 84a6c723a6..cade2181cf 100644
--- a/quantum/openstack/common/rpc/common.py
+++ b/quantum/openstack/common/rpc/common.py
@@ -19,10 +19,8 @@
 
 import copy
 import logging
-import sys
 import traceback
 
-from quantum.openstack.common import cfg
 from quantum.openstack.common.gettextutils import _
 from quantum.openstack.common import importutils
 from quantum.openstack.common import jsonutils
diff --git a/quantum/openstack/common/rpc/impl_zmq.py b/quantum/openstack/common/rpc/impl_zmq.py
index 3396ef3720..f4fcce0389 100644
--- a/quantum/openstack/common/rpc/impl_zmq.py
+++ b/quantum/openstack/common/rpc/impl_zmq.py
@@ -72,7 +72,7 @@ zmq_opts = [
 
 # These globals are defined in register_opts(conf),
 # a mandatory initialization call
-FLAGS = None
+CONF = None
 ZMQ_CTX = None  # ZeroMQ Context, must be global.
 matchmaker = None  # memoized matchmaker object
 
@@ -274,7 +274,7 @@ class InternalContext(object):
             ctx.replies)
 
         LOG.debug(_("Sending reply"))
-        cast(FLAGS, ctx, topic, {
+        cast(CONF, ctx, topic, {
             'method': '-process_reply',
             'args': {
                 'msg_id': msg_id,
@@ -329,7 +329,6 @@ class ZmqBaseReactor(ConsumerBase):
     def __init__(self, conf):
         super(ZmqBaseReactor, self).__init__()
 
-        self.conf = conf
         self.mapping = {}
         self.proxies = {}
         self.threads = []
@@ -405,7 +404,7 @@ class ZmqProxy(ZmqBaseReactor):
         super(ZmqProxy, self).__init__(conf)
 
         self.topic_proxy = {}
-        ipc_dir = conf.rpc_zmq_ipc_dir
+        ipc_dir = CONF.rpc_zmq_ipc_dir
 
         self.topic_proxy['zmq_replies'] = \
             ZmqSocket("ipc://%s/zmq_topic_zmq_replies" % (ipc_dir, ),
@@ -413,7 +412,7 @@ class ZmqProxy(ZmqBaseReactor):
         self.sockets.append(self.topic_proxy['zmq_replies'])
 
     def consume(self, sock):
-        ipc_dir = self.conf.rpc_zmq_ipc_dir
+        ipc_dir = CONF.rpc_zmq_ipc_dir
 
         #TODO(ewindisch): use zero-copy (i.e. references, not copying)
         data = sock.recv()
@@ -487,7 +486,6 @@ class Connection(rpc_common.Connection):
     """Manages connections and threads."""
 
     def __init__(self, conf):
-        self.conf = conf
         self.reactor = ZmqReactor(conf)
 
     def create_consumer(self, topic, proxy, fanout=False):
@@ -508,7 +506,7 @@ class Connection(rpc_common.Connection):
 
         # Receive messages from (local) proxy
         inaddr = "ipc://%s/zmq_topic_%s" % \
-            (self.conf.rpc_zmq_ipc_dir, topic)
+            (CONF.rpc_zmq_ipc_dir, topic)
 
         LOG.debug(_("Consumer is a zmq.%s"),
                   ['PULL', 'SUB'][sock_type == zmq.SUB])
@@ -527,7 +525,7 @@ class Connection(rpc_common.Connection):
 
 
 def _cast(addr, context, msg_id, topic, msg, timeout=None):
-    timeout_cast = timeout or FLAGS.rpc_cast_timeout
+    timeout_cast = timeout or CONF.rpc_cast_timeout
     payload = [RpcContext.marshal(context), msg]
 
     with Timeout(timeout_cast, exception=rpc_common.Timeout):
@@ -545,13 +543,13 @@ def _cast(addr, context, msg_id, topic, msg, timeout=None):
 
 def _call(addr, context, msg_id, topic, msg, timeout=None):
     # timeout_response is how long we wait for a response
-    timeout = timeout or FLAGS.rpc_response_timeout
+    timeout = timeout or CONF.rpc_response_timeout
 
     # The msg_id is used to track replies.
     msg_id = str(uuid.uuid4().hex)
 
     # Replies always come into the reply service.
-    reply_topic = "zmq_replies.%s" % FLAGS.rpc_zmq_host
+    reply_topic = "zmq_replies.%s" % CONF.rpc_zmq_host
 
     LOG.debug(_("Creating payload"))
     # Curry the original request into a reply method.
@@ -573,7 +571,7 @@ def _call(addr, context, msg_id, topic, msg, timeout=None):
     with Timeout(timeout, exception=rpc_common.Timeout):
         try:
             msg_waiter = ZmqSocket(
-                "ipc://%s/zmq_topic_zmq_replies" % FLAGS.rpc_zmq_ipc_dir,
+                "ipc://%s/zmq_topic_zmq_replies" % CONF.rpc_zmq_ipc_dir,
                 zmq.SUB, subscribe=msg_id, bind=False
             )
 
@@ -599,7 +597,7 @@ def _call(addr, context, msg_id, topic, msg, timeout=None):
     # responses for Exceptions.
     for resp in responses:
         if isinstance(resp, types.DictType) and 'exc' in resp:
-            raise rpc_common.deserialize_remote_exception(FLAGS, resp['exc'])
+            raise rpc_common.deserialize_remote_exception(CONF, resp['exc'])
 
     return responses[-1]
 
@@ -610,7 +608,7 @@ def _multi_send(method, context, topic, msg, timeout=None):
     dispatches to the matchmaker and sends
     message to all relevant hosts.
     """
-    conf = FLAGS
+    conf = CONF
     LOG.debug(_("%(msg)s") % {'msg': ' '.join(map(pformat, (topic, msg)))})
 
     queues = matchmaker.queues(topic)
@@ -641,26 +639,22 @@ def create_connection(conf, new=True):
 
 def multicall(conf, *args, **kwargs):
     """Multiple calls."""
-    register_opts(conf)
     return _multi_send(_call, *args, **kwargs)
 
 
 def call(conf, *args, **kwargs):
     """Send a message, expect a response."""
-    register_opts(conf)
     data = _multi_send(_call, *args, **kwargs)
     return data[-1]
 
 
 def cast(conf, *args, **kwargs):
     """Send a message expecting no reply."""
-    register_opts(conf)
     _multi_send(_cast, *args, **kwargs)
 
 
 def fanout_cast(conf, context, topic, msg, **kwargs):
     """Send a message to all listening and expect no reply."""
-    register_opts(conf)
     # NOTE(ewindisch): fanout~ is used because it avoid splitting on .
     # and acts as a non-subtle hint to the matchmaker and ZmqProxy.
     _multi_send(_cast, context, 'fanout~' + str(topic), msg, **kwargs)
@@ -672,7 +666,6 @@ def notify(conf, context, topic, msg, **kwargs):
     Notifications are sent to topic-priority.
     This differs from the AMQP drivers which send to topic.priority.
     """
-    register_opts(conf)
     # NOTE(ewindisch): dot-priority in rpc notifier does not
     # work with our assumptions.
     topic.replace('.', '-')
@@ -684,7 +677,7 @@ def cleanup():
     global ZMQ_CTX
     global matchmaker
     matchmaker = None
-    ZMQ_CTX.destroy()
+    ZMQ_CTX.term()
     ZMQ_CTX = None
 
 
@@ -697,11 +690,11 @@ def register_opts(conf):
     # We memoize through these globals
     global ZMQ_CTX
     global matchmaker
-    global FLAGS
+    global CONF
 
-    if not FLAGS:
+    if not CONF:
         conf.register_opts(zmq_opts)
-        FLAGS = conf
+        CONF = conf
     # Don't re-set, if this method is called twice.
     if not ZMQ_CTX:
         ZMQ_CTX = zmq.Context(conf.rpc_zmq_contexts)
diff --git a/quantum/openstack/common/timeutils.py b/quantum/openstack/common/timeutils.py
index 67327478a9..c4f6cf0497 100644
--- a/quantum/openstack/common/timeutils.py
+++ b/quantum/openstack/common/timeutils.py
@@ -93,13 +93,13 @@ def set_time_override(override_time=datetime.datetime.utcnow()):
 
 
 def advance_time_delta(timedelta):
-    """Advance overriden time using a datetime.timedelta."""
+    """Advance overridden time using a datetime.timedelta."""
     assert(not utcnow.override_time is None)
     utcnow.override_time += timedelta
 
 
 def advance_time_seconds(seconds):
-    """Advance overriden time by seconds."""
+    """Advance overridden time by seconds."""
     advance_time_delta(datetime.timedelta(0, seconds))
 
 
@@ -122,6 +122,5 @@ def marshall_now(now=None):
 def unmarshall_time(tyme):
     """Unmarshall a datetime dict."""
     return datetime.datetime(day=tyme['day'], month=tyme['month'],
-                             year=tyme['year'], hour=tyme['hour'],
-                             minute=tyme['minute'], second=tyme['second'],
-                             microsecond=tyme['microsecond'])
+                 year=tyme['year'], hour=tyme['hour'], minute=tyme['minute'],
+                 second=tyme['second'], microsecond=tyme['microsecond'])
diff --git a/quantum/plugins/nicira/nicira_nvp_plugin/common/config.py b/quantum/plugins/nicira/nicira_nvp_plugin/common/config.py
index da2e8d8f9d..c9875dffae 100644
--- a/quantum/plugins/nicira/nicira_nvp_plugin/common/config.py
+++ b/quantum/plugins/nicira/nicira_nvp_plugin/common/config.py
@@ -61,10 +61,12 @@ class ClusterConfigOptions(cfg.CommonConfigOpts):
         """
         if group is None and name in self._groups:
             return self.GroupAttr(self, self._get_group(name))
+
         info = self._get_opt_info(name, group)
-        default, opt, override = [info[k] for k in sorted(info.keys())]
-        if override is not None:
-            return override
+        opt = info['opt']
+
+        if 'override' in info:
+            return info['override']
 
         values = []
         if self._cparser is not None:
@@ -96,8 +98,8 @@ class ClusterConfigOptions(cfg.CommonConfigOpts):
         if values:
             return values
 
-        if default is not None:
-            return default
+        if 'default' in info:
+            return info['default']
 
         return opt.default