Comment 2 for bug 863394

Steps to replicate

From a clean booted Lucid server (cloud image or otherwise).

sudo apt-get update
sudo apt-get dist-upgrade
sudo apt-get install bridge-utils dnsmasq-base ruby
Install the attached files (bradd.sh, create-bridges.rb) in the home directory and run

sudo ./create-bridges.rb 25 50
System will create bridges up to br25006e (the 28th bridge) and then fail with

dnsmasq: no interface with address 2a02:1348:134:401b:24:19ff:fe25:6e
You can start the sequence again with another set of bridges

sudo ./create-bridges.rb 26 50
'26' is the prefix differentiator and '50' is the number of bridges you want.

It doesn't appear to fail again.