[Mediawiki-l] Cannot upgrade beyond 1.6.12?

[Ragansi]

  I'm working on a wiki that has been sitting at version 1.3.9 for 
"quite some time" without upgrades. I've not been able to upgrade beyond 
1.6.12.  The upgrade path is direct from that point.  I download the 
tarball for 1.6.12, unpack it, run the update.php script and all is 
well.  0 problems.

The pages load fine, everything is editable, the CLI returns no errors 
or warnings.  What strikes me as odd is that if I try and do a "direct 
upgrade" from 1.3.9 to anything beyond 1.6.12 all I get is a white 
screen.  Running php from the CLI results in the following messages:

PHP Notice:  Undefined index:  REQUEST_METHOD in 
/var/apache2/2.2/htdocs/includes/Setup.php on line 223
PHP Notice:  Undefined index:  REQUEST_METHOD in 
/var/apache2/2.2/htdocs/includes/WebRequest.php on line 439

With the exception of 1.15.1, in which case I only get the second message.

I'm not all that sure of what the problem is at this point, or even 
where I should be looking for answers.  I've tried enabling logging, 
been googleing this for over a week at this point, and I'm not even sure 
which direction to go next.  A pointer in most any direction is utmostly 
appreciated.

I have attempted the upgrades on the following operating systems and 
various versions of PHP 5 as well:
Solaris 10, OpenIndiana, CentOS, Debian.  They all result in the same 
outcome, which indicates to me that apache and php are not likely the 
problem, but I'm ruling them out either.