Previously we had opened port 5000 for the buildset registry. But we
also run a buildset registry proxy on port 5001. Because docker manages
the ipv4 firewall rules itself it was opening ipv4 5001 but ignoring
ipv6 5001. This meant that jobs that use ipv6 addrs as primary addrs
were failing to talk ot the registry proxy.
Fix this by opening the range 5000:5001.
Change-Id: I88abcd7fd99fb7dcc7726ef9a52f9b022729f9d5
dbb56dda99