MySQL Master Port is collected but not used in multiserver setup of slave servers
In case you have the master MySQL server running on a custom port, the config script is not implementing this option into the code even if it is collected from the input console.
Check install/install.php line 267 where this detail is collected (custom MySQL port).
Then at install/install.php line 282 will fail because there is no MySQL server running at the standard port.
This bug may break your install in case of tunnel/proxy mysql remote server.