ovs-fw: Don't modify passed rules to update

When rules are passed to update() method of firewall, it translates
protocol in case it was passed as a string to integer. This can cause a
side-effect in testing when same set of rules is passed multiple times.
Securiry group rules always have a string in protocol field.

Change-Id: I0d95c6c41ad3c4b52986307449d90f13bbd412ac

neutron/agent/linux/openvswitch_firewall/firewall.py

@@ -14,6 +14,7 @@
 #    under the License.
 
 import collections
+import copy
 
 import netaddr
 from neutron_lib import constants as lib_const
@@ -91,7 +92,7 @@ class SecurityGroup(object):
         """
         self.raw_rules = []
         self.remote_rules = []
-        for rule in rules:
+        for rule in copy.deepcopy(rules):
             protocol = rule.get('protocol')
             if protocol is not None:
                 if protocol.isdigit():