AFAIK this behavior dates back to changes in ubiquity circa Maverick. Prior to that the final installation screen allowed the user to select where they wished to install grub but beginning with Maverick a user may only change where grub is going to be installed using the advanced partitioning option.
This may be a duplicate of bug 684292.
AFAIK this behavior dates back to changes in ubiquity circa Maverick. Prior to that the final installation screen allowed the user to select where they wished to install grub but beginning with Maverick a user may only change where grub is going to be installed using the advanced partitioning option.