Here's a 'diff -u' which is the original patch, but against the base at rev 1806, and with one slight change making the override of ADMINDB_PAGE_TEXT_LIMIT with -1 contingent on HOLD_MESSAGES_AS_PICKLES == 0 which latter setting is required for this to work at all.
This patch will apply cleanly, but is untested and comes with no assertions as to its efficacy.
** Attachment added: "diff -u" https://bugs.launchpad.net/mailman/+bug/557995/+attachment/5234872/+files/ed...