drupal_override_server_variables() does not properly override SCRIPT_NAME

d_o_s_v() is, according to the documentation, a function to be used by CLI scripts for populating server variables. Of particular interest is the special "url" key, which is split up into host and path and written into the appropriate variables.

However, the structure goes like this:

  $defaults = array(
    'HTTP_HOST' => $url['host'],
    'SCRIPT_NAME' => $url['path'],
    // ...
  );

  $_SERVER = $variables + $_SERVER + $defaults;

First of all, this never works at all on the web, because $_SERVER contains both of these variables and overrides them implicitly since array addition is left-sided.

In CLI scripts, we see an even stranger effect: The HTTP_HOST is populated, because $_SERVER doesn't have it. But "SCRIPT_NAME" is in PHP CLI's $_SERVER, which means that while our "url" key overrides the HTTP_HOST, it doesn't do anything to SCRIPT_NAME.

These two variables need to be written into a separate array instead, which takes precedence over $_SERVER.