This was introduced in 1.4.1 with d26c147.

This PR sets the active hostname back to the name specified in the Vagrantfile (fqdn) and updates the unit tests.

Setting it to the short name causes loads of problems while configuring the system. I've had issues with sudoers hostname matching, Weblogic certificate generation and a few others. Even if I changed all of the Chef recipes, the fqdn is set in /etc/sysconfig/network so the active hostname will switch to the fqdn after a reboot.
Merge pull request #2792 from smoyer/redhat_hostname_patch

guests/redhat: use FQDN for hostname