When using the mod_ssl state on Red Hat family systems the httpd
server will currently not start.
This is due to duplicate Listen directives provided in the
ssl.conf file shipped with the mod_ssl rpm package and the directives
configured by saltstack.
The easy solution is to just ensure the rpm shipped mod_ssl is removed.
Other states in this formula allow changing the Apache httpd or module
package on RHEL/CentOS, e.g., one may use packages from the httpd24
SCL to install newer versions than in the base repositories. This
changes the apache.mod_ssl SLS to match them.