[Mediawiki-l] setting mediawiki 1.2.6 to read-only mode?

[JT.Thomas at VerizonWireless.com]

dang-it I could swear I've seen this addressed already on the list, or on
meta, but I can't seem to find it.

Is there a line you can add to LocalSettings.php to set mediawiki 1.2.6 to
read-only mode?

I want to be able to do this so I can do a parallel upgrade to 1.3.0 while
keeping a copy available for consumption (but no editing of content) to the
users.

Best Regards,

JT