Last modified: 2014-01-20 14:33:50 UTC
At https://en.wikipedia.org/w/index.php?title=Decisions_%28song%29&action=history , the revision at 01:46, 19 January 2014 is 12,596 bytes, and the revision immediately before it at 00:53, 19 January 2014 is 12,549 bytes, but the size delta between the revisions is 0. These revisions were created in this way as a result of a history merge.
The problem is that rev_parent_id no longer points to the previous revision after a history merge.