I ran into an issue (When using fpm, it is not clear how to make image styles work
) which I traced back to the use of Drupal_Security_Do_Not_Remove_See_SA_2006_006 in sites/default/files/.htaccess
.
In order to continue debugging I would need a more solid understanding of what exactly "SetHandler Drupal_Security_Do_Not_Remove_See_SA_2006_006" does in that file, because when I comment it out, my issue is resolved.
Is there code somewhere which "Handles" files? If so where? I have searched Drupal and cannot find any actual logic behind this.