BUG #14477: Can't start service because of upgrade-like installation

The following bug has been logged on the website:

Bug reference: 14477
Logged by: Meirav Rath
Email address: meirav(dot)rath(at)imperva(dot)com
PostgreSQL version: 9.6.1
Operating system: RHEL 6.5 x64
Description:

Hi,
I just installed Postgres 9.6.1 on a machine that did not have any version
of this database on it.
I used the EDB installer and chose every default option in the various
question.

My problems are:
1. There was no /pgsql/data directory created - postgresql.conf is located
in /opt/PostgreSQL/9.6/data.
2. I tried to start the database with:

-bash-4.1$ postgres -D /opt/PostgreSQL/9.6/data
2016-12-25 17:02:30 IST FATAL: database files are incompatible with
server
2016-12-25 17:02:30 IST DETAIL: The data directory was initialized by
PostgreSQL version 9.6, which is not compatible with this version 8.4.20.

I did not download 8.4.2 rpm....