Path verification on NT sometimes fails due to case of drive letter.
Imported from https://youtrack.roxen.com/issue/PIKE-105
Reported by @grubba
%% Request for /webdav/.htaccess
%% URL module mod: Authentication: .htaccess support
%% Location module [/webdav/] mod: /webdav/ from c:/distt.../webdav/
%% Calling find_file()...
%% find_file(".htaccess")
Path verification of ".htaccess" failed:
"c:\\disttest\\install test\\ws_6_2\\var\\testsuite\\webdav\\" is not a prefix of "C:\\disttest\\install test\\ws_6_2\\var\\testsuite\\webdav\\.htaccess"
%% Permission denied.
%% Returned 403.