I think it's likely creating a new OS if the exact major/minor numbers aren't found on the existing OS, this might contain the ".4" too.

There are at least three problems here, all of which are caused by Foreman reassigning the Operating System out from under us.

Problem 1: I assigned the host an OS, but Foreman invented a new OS entry instead of leaving it alone.

Problem 2: I assigned the host an OS, but Foreman reassigned the host to a different OS with the same name and version, because two entries with matching name and version numbers could be returning in different order from the database at different queries. Instead of leaving it alone.

Problem 3: I assigned the host an OS, and months later did a package upgrade which changed the OS micro version, causing Foreman to reassign the OS instead of leaving it alone.

We have operating System entries like "Ubuntu 12.04 + 3.2.0 kernel" and "Ubuntu 12.04 + 3.13.0 kernel". Based on which OS I assigned to a machine, I have different netboot, templates, and parameters. These are set up as:

Name: Ubuntu
    Major: 12
    Minor: 04
    Description: + 3.2.0 kernel
    / Description: + 3.13.0 kernel
    / Description: with alternate netboot, etc.

Can we disable Foreman from reassigning the OS based on the received facts?

Should we be using some other mechanism to control the host OS installation parameters!?

https://groups.google.com/forum/#!topic/foreman-dev/d2OWhUG3J_A has some discussion.