Revert "remove external_network_bridge option"

This reverts commit faaf96b.

Ironic jobs were still using this option, it needs to be
switched to an alternative first.

Change-Id: I1683d7cfa81f5fe2497cc7045e87f8b20fed4968

Author: derekhiggins

lib/neutron

@@ -95,6 +95,9 @@ NEUTRON_ROOTWRAP_CONF_FILE=$NEUTRON_CONF_DIR/rootwrap.conf
 NEUTRON_ROOTWRAP_CMD="$NEUTRON_ROOTWRAP $NEUTRON_ROOTWRAP_CONF_FILE"
 NEUTRON_ROOTWRAP_DAEMON_CMD="$NEUTRON_ROOTWRAP-daemon $NEUTRON_ROOTWRAP_CONF_FILE"
 
+# This is needed because _neutron_ovs_base_configure_l3_agent will set
+# external_network_bridge
+Q_USE_PROVIDERNET_FOR_PUBLIC=${Q_USE_PROVIDERNET_FOR_PUBLIC:-True}
 # This is needed because _neutron_ovs_base_configure_l3_agent uses it to create
 # an external network bridge
 PUBLIC_BRIDGE=${PUBLIC_BRIDGE:-br-ex}

lib/neutron_plugins/ovs_base

@@ -96,6 +96,10 @@ function _neutron_ovs_base_configure_firewall_driver {
 }
 
 function _neutron_ovs_base_configure_l3_agent {
+    if [ "$Q_USE_PROVIDERNET_FOR_PUBLIC" != "True" ]; then
+        iniset $Q_L3_CONF_FILE DEFAULT external_network_bridge $PUBLIC_BRIDGE
+    fi
+
     neutron-ovs-cleanup --config-file $NEUTRON_CONF
     if [[ "$Q_USE_PUBLIC_VETH" = "True" ]]; then
         ip link show $Q_PUBLIC_VETH_INT > /dev/null 2>&1 ||