yum: Fix apt-dater-host with newlines in yum

Blergh. I not only deleted the remote branch on github but also my local one and reflog doesn't show anything (seriously!). The commit below is the one I could restore from my backups - if you do a have a copy of my branch please diff if there is anything different besides the missing 'warn' for debugging purposes.

Else, I'm just referring to https://github.com/DE-IBH/apt-dater-host/pull/2#issuecomment-20368120 - which can't be read anymore. Sorry.

Sebastian