Comment 7 for bug 1379607

changing hostname will cause corosync command can't work properly like:
ubuntu@juju-zhhuabj-machine-5:~$ sudo crm node online
sudo: unable to resolve host neutron-gateway
Could not map name=neutron-gateway to a UUID
Please choose from one of the matches above and suppy the 'id' with --attr-id

this is because we change the hostname to neutron-gateway but corosync still use initial hostname juju-zhhuabj-machine-5
can also refer the data https://pastebin.canonical.com/119639/

this is only one problem I found caused by the same hostname, not sure if exist other problems, It's too expensive to use same hostname, so I think using router migration will be more better choice.