There was something in the Factory Mailing today about the repos in slowroll. I can confirm that these new repos work.
https://en.opensuse.org/openSUSE:Slowroll
Here is what needs to be run as root:
rm /etc/zypp/repos.d/*
zypper ar --refresh http://cdn.opensuse.org/slowroll/repo/oss/ base-oss
zypper ar --refresh http://cdn.opensuse.org/slowroll/repo/non-oss/ base-non-oss
zypper ar --refresh -p 80 http://cdn.opensuse.org/update/slowroll/repo/oss/ update
zypper ar --refresh --disable http://cdn.opensuse.org/slowroll/repo/src-oss/ base-src-oss
zypper ar --refresh http://codecs.opensuse.org/openh264/openSUSE_Tumbleweed/ h264
zypper ar --refresh -p 70 http://ftp.gwdg.de/pub/linux/misc/packman/suse/openSUSE_Slowroll/Essentials/ packman