[Super Cache] wp-config permissions changed on activation / deactivation

[thingalon]

Relevant link: https://wordpress.org/support/topic/wp-config-php-permissions-set-to-600/

A user has observed that their wp-config.php file had its permissions changed from 644 to 600 during installation and uninstallation of Super Cache.

Super Cache updates wp-config.php to add the WP_CACHE and WPCACHEHOME constants to facilitate managing the cache before WordPress (and the connection to its database) has finished loading. To do so safely, Super Cache copies wp-config.php to a new file with the relevant edits - then renames the new file in place of the old one. Along the way, it doesn't copy the file permissions from the original wp-config.php to the new one.

We should add a chmod to the process to ensure the updated wp-config.php file has the same permissions as the original.