Failure to commission when interfaces has a /32 IP

[Björn Tillenius]

If a controller has an interface that has one IP on a subnet, and another IP that is within the same subnet, but with a /32 mask, the proxy may deny requests from that bigger subnet.

For example:

1: broam: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
     link/ether 1c:98:ec:21:98:54 brd ff:ff:ff:ff:ff:ff
   inet 10.244.40.30/21 brd 10.244.47.255 scope global broam
      valid_lft forever preferred_lft forever
   inet 10.244.40.34/32 brd 10.244.47.255 scope global broam
      valid_lft forever preferred_lft forever

In 2.9 MAAS would special-case this and detect only the 10.244.40.0/21 subnet. 3.0 on the other hand creates both the 10.244.40.0/21 subnet, and 10.244.34/32.

Now, if the /32 subnet is before the /21 subnet in the proxy config, requests from the whole /21 subnet will be denied.

2.9 has logic for in fix_link_addresses() to make those /32 be /21 instead. We need to do the same thing in 3.0.