Windows 8 built-in WebDAV client ignores 401 Unauthorized

Question

I create a webdav connection with the Windows 8 built-in WebDAV client (Microsoft-WebDAV-MiniRedir).
I have only a read permission for the files and try to delete one.
I can open by right-click the context menu and delete it, although my WebDAV server returns 401 Unauthorized. The file disappears in the explorer as if it has been deleted.
If I close the explorer window and open it again, the file is back again, what is ok.
Why the deletion is not refused and why I doesn't get from the WebDAV client an error message like "401 unauthorized access"?

Here are the request and response.
Request:

DELETE https://xxx.yyy.zz/webdav/mysharedfolder/file1.txt HTTP/1.1
Connection: Keep-Alive
User-Agent: Microsoft-WebDAV-MiniRedir/6.3.9600
translate: f
Host: xxx.yyy.zz
Authorization: Basic dlk7uXNvcmt1QHdlYi5kZTpRd2VyMTIzNA==
Cookie: JSESSIONID=A7497F42472ECC676E44A90E3C5D5E7

Response:

HTTP/1.1 401 Unauthorized
Date: Thu, 13 Nov 2014 23:21:43 GMT
Server: Apache-Coyote/1.1
WWW-Authenticate: Basic realm="https://xxx.yyy.zz/webdav/mysharedfolder/file1.txt"
Content-Length: 0
Connection: close
Content-Type: text/plain; charset=UTF-8

Answer 1

A redirect on an OPTIONS request (or in any webdav request actually) is suspicious, and I wouldnt assume windows will correctly handle that, so that might be something to look at. But i also vaguely remember encountering something similar with Win7 years ago. A workaround might be to return a different 4xx error code for the mini-redirector agent.