Wikimedia Bugzilla is closed!

"HTTP lint" of a MediaWiki 1.5.6 install gives one error for the HTTP headers,
namely:
-----------------------
# Expires: -1[0d][0a]
    * Error: Failed to parse this date. Dates should be in the RFC 1123 format.
-----------------------

Appears to originate from includes/OutputPage.php :
-----------------------
[holt]$ grep -inr "Expires:" *
includes/OutputPage.php:387:                            header( "Expires: -1" );
includes/OutputPage.php:396:                    header( 'Expires: -1' );
[holt]$
-----------------------

The RFCs ( http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.21 ) say:
"The format is an absolute date and time as defined by HTTP-date in section
3.3.1; it MUST be in RFC 1123 date format."

They also say: HTTP/1.1 clients and caches MUST treat other invalid date
formats, especially including the value "0", as in the past (i.e., "already
expired").

So, "-1" gets treated as invalid (and thus gets treated as being in the past).
The RFC suggests it would be more correct to instead give a date sometime in the
past, in RFC 1123 format.