If you run `newgrp kvm` after the user-setup script completes, and then
proceed to run `make build`, `make autospec`, etc. within a package
repo, mock will fail because it tries to `groupadd mockbuild` in the
package chroot with the wrong group ID. Logging out and logging back in
results in correct behavior, so leave that as the sole recommendation.
Signed-off-by: Patrick McCarty <patrick.mccarty@intel.com>