Context: To enable detection of changes in moved paragraphs, a new (fourth) parameter is going to be added to wikidiff2_do_diff(). That new parameter controls the maximum number of paragraphs to compare, and will have a default value for backwards compatibility (probably 25 or so). Setting it to 0 will cause detection of moved paragraph detection to be disabled, returning wikidiff2_do_diff to the previous behavior.
We need a MediaWiki configuration variable to control this, named $wgWikiDiff2MoveParagraphDetectionCutoff or some such. That variable should default to (probably) 25.
For deployment, $wgWikiDiff2MoveParagraphDetectionCutoff should initially be set to 0, so on-wiki behavior does not change.
Once this has been done, the new version of wikidiff2 can be rolled out to the production servers.
The next step would be to set it to 25 or something on test.wikipedia.org to expose it to the community for testing. Once testing is complete, set it to 25 (or something) on all wikis.