The entirety of my vhost.conf:

Alias /site_media /var/www/vhosts/mysite.com/subdomains/dev/python/nautsite/media
Alias /admin_media /var/www/vhosts/mysite.com/subdomains/dev/python/django/contrib/admin/media
Alias /php /var/www/vhosts/mysite.com/subdomains/dev/python/nautsite/php

requests to
http://dev.mysite.com/test.php get interpreted correctly

requests to
http://dev.mysite.com/php/test.php prompt a file download, and do not get interpreted as php