It is not recommended you do this because you may run into issues. For example, some changes were made in crypto_master.php and data/upgrader2.php prior to the first v11 alpha. These changes will result in a broken upgrade unless you already pulled these changes from git. Similar situations could happen in the future as well.

It is recommended you either discard the git install and use a fresh install from the Downloads, or to maintain a git install and a bleeding-edge release install separately. Do not combine the two.