Update db entry before upate the DHCP host file.

Update fixed IP db entry before upated the DHCP host file.

Fixes LP Bug #1078718

Change-Id: I75504acfc1c571219938d25a7c3b1a452d3f1cb9
(cherry picked from commit 5149080)

nova/network/manager.py

@@ -1321,6 +1321,10 @@ def deallocate_fixed_ip(self, context, address, host=None, teardown=True):
                 self.instance_dns_manager.delete_entry(n,
                                                       self.instance_dns_domain)
 
+        self.db.fixed_ip_update(context, address,
+                                {'allocated': False,
+                                 'virtual_interface_id': None})
+
         if teardown:
             network = self._get_network_by_id(context,
                                               fixed_ip_ref['network_id'])
@@ -1347,10 +1351,6 @@ def deallocate_fixed_ip(self, context, address, host=None, teardown=True):
                 #             callback will get called by nova-dhcpbridge.
                 self.driver.release_dhcp(dev, address, vif['address'])
 
-        self.db.fixed_ip_update(context, address,
-                                {'allocated': False,
-                                 'virtual_interface_id': None})
-
     def lease_fixed_ip(self, context, address):
         """Called by dhcp-bridge when ip is leased."""
         LOG.debug(_('Leased IP |%(address)s|'), locals(), context=context)