I'm trying to install 9.6 RC1 on Ubuntu 16.04 Xenial on my laptop and it seems broken.
Installation of 9.6 RC1 on Centos was straightforward by comparison - just add the 9.6 yum package and install. Unfortunately Ubuntu seems second-class by comparison.
This works and I previously installed the PGDG 9.5 package without issue. Apt lists numerous 9.6 support packages (unit, repmgr, repack, plv8, ...) but with unsatisfied dependencies due to the lasck of postgresql-9.6.