[Mason] [warn] Use of uninitialized value at /usr/local/lib/perl5/site_perl/HTML/Mason/Request.pm line 407.

[<li...@ar...>]

I've been getting quite a few of these warning since upgrading to Mason
1.0.  It has taken me a bit to figure out the cause of the problem (the
solution is easy).  On a HEAD request, 
HTML::Mason::ApacheHandler::handle_request_1 is calling
HTML::Mason::Request::depth, which then returns $REQ_DEPTH.  However,
$REQ_DEPTH has yet to be set.  Changing the parenthesis around in
HTML::Mason::Request::depth to the following solves the problem :

     return((($REQ eq $self) ? $REQ_DEPTH : $REQ_DEPTHS{$self}) || 0); 

Why was I getting "many" HEAD requests?  Because I have big brother
watching all my web sites (20+ of them), which means a HEAD request every
10 minutes or so.

-Philip