Hi Devrim,
Currently having the PostgreSQL yum repositories installed is really risky business because it will obsolete many stock packages apart from postgresql-server itself. This is really something you would want to avoid.
Just checking up on the idea of issuing a warning regarding the non-safe nature of the PostgreSQL yum repository, perhaps on https://yum.postgresql.org and in the yum repo file. Perhaps it is also a good idea to provide a list of conflicting/obsoleting packages?
(Ideally this warning would not be necessary, when there would be a separation of yum repositories into safe and non-safe.)
Kind regards,
Pim Rupert