Just in case, if we uninstall, the exisiting 5.6.13 version of MySQL...will this yum command proceed to install the stable MySQL version(i.e., 5.1.73)?
As I am trying to install Phabricator for the first time, kindly guide with your inputs.

Yeah. we have installed "MySQL-server-5.6.13-1.el6.x86_64".
But in the logs, we could see
"---> Package mysql-server.x86_64 0:5.1.73-3.el6_5 will be installed"
In the pre-requisites too, you have mentioned, 'MySQL 5.5 or above is required.
Then why is it searching for 5.1.73 version?