GET/HEAD calls on directories don't respect the RFC

[danieletorelli]

Describe the bug
If I do a GET call on the root directory or another existing directory, it responds with 404 Not Found:

< HTTP/1.1 404 Not Found

<?xml version="1.0" encoding="utf-8"?>
<D:multistatus xmlns:D="DAV:">
  <D:response>
    <D:href>/</D:href>
    <D:propstat>
      <D:prop/>
      <D:status>HTTP/1.1 404 NOT FOUND</D:status>
    </D:propstat>
  </D:response>
</D:multistatus>

and the HEAD call responds with 403 Forbidden:

< HTTP/1.1 403 Forbidden

this behaviour is not standard and doesn't respect the RFC4918.

Expected behavior
I'd instead expect to receive 404 only for directories that don't exist and at least a 200 Ok response, even if with no body, for directories that exist both for GET and HEAD calls.

Please check the corresponding section in the RFC: http://www.webdav.org/specs/rfc4918.html#rfc.section.9.4