packages: ignore yum check-update returned code
packages: ignore yum check-update returned code

“yum check-update” execution code is not really useful, we ignore it for
the moment.

Retcode:
 - 0: success
 - 100: success with update packages to install
 - 0: RHN communication failure ( https://access.redhat.com/site/solutions/72573 )

enovance/edeploy,lebauce/edeploy,redhat-cip/edeploy,redhat-cip/edeploy,enovance/edeploy,lebauce/edeploy,enovance/edeploy,lebauce/edeploy,redhat-cip/edeploy,lebauce/edeploy,enovance/edeploy,redhat-cip/edeploy