I had the same problem yesterday on a fresh install.
I managed to solve it using the solution in this topic:
modifying the setup script and replacing:
wget -O /etc/apt/trusted.gpg.d/flair.asc https://cern.ch/flair/download/ubuntu/flair.gpg 2>> $logfile
with
wget -O /etc/apt/trusted.gpg.d/flair.asc http://cern.ch/flair/download/ubuntu/flair.gpg 2>> $logfile
without the s in http.