Comment 14 for bug 1431386

And another comment from Evgeniy with more detailed explanation:

"We follow the next approaches depending on the task:

1. ask user to reboot nodes explicitly, we can notify user that there are nodes from another master node and ask him/her to reboot those bootstrap nodes

2. for other cases we do reboot from master node only, only Nailgun knows everything about nodes and in what state they are, so we do reboot in case of provisioning for example. It won't work here, because MCollective is not going to work.

To fix this particular issue, it's better to reject nodes creation on API level and create notification, with explanation, that some nodes, which were booted/installed with another fuel installation, are trying to perform discovery."