Normalize MAC addresses from netbox to lowercase

Both tools used to gather MAC addresses from devices (ethtool and
/sys/class/net) return mac addresses as lowercase, but netbox normalizes them
as uppercase, causing spurious MAC delete/re-creates when updating servers as
the macs don't compare equal

Author: Anatole Denis

netbox_agent/network.py

@@ -294,12 +294,12 @@ def update_interface_macs(self, nic, macs):
         nb_macs = list(self.nb_net.mac_addresses.filter(interface_id=nic.id))
         # Clean
         for nb_mac in nb_macs:
-            if nb_mac.mac_address not in macs:
+            if nb_mac.mac_address.lower() not in macs:
                 logging.debug("Deleting extra MAC {mac} from {nic}".format(mac=nb_mac, nic=nic))
                 nb_mac.delete()
         # Add missing
         for mac in macs:
-            if mac not in {nb_mac.mac_address for nb_mac in nb_macs}:
+            if mac not in {nb_mac.mac_address.lower() for nb_mac in nb_macs}:
                 logging.debug("Adding MAC {mac} to {nic}".format(mac=mac, nic=nic))
                 self.nb_net.mac_addresses.create(
                     {
@@ -542,7 +542,7 @@ def batched(it, n):
                 if nic["mac"]:
                     self.update_interface_macs(interface, [nic["mac"]])
 
-            if nic["mac"] and nic["mac"] != interface.mac_address:
+            if nic["mac"] and nic["mac"] != interface.mac_address.lower():
                 logging.info(
                     "Updating interface {interface} mac to: {mac}".format(
                         interface=interface, mac=nic["mac"]