Apparently, undeletion no longer sets the parent ids for the undeleted revisions to the "expected" one given by the previous revision by id (usually, but not always, also the previous revision by timestamp), but instead to the ar_parent_id values. For example, look at the [[https://en.wikipedia.org/w/index.php?title=Ernest_Madu&action=history|history of Ernest Madu on Wikipedia]], and you'll see that [[https://en.wikipedia.org/w/index.php?title=Ernest_Madu&oldid=820864133|revision 820864133]] has parent id 0 (with an "N" mark in the [[https://en.wikipedia.org/wiki/Special:Contributions/Andrewkazimi|user's contribs]]) instead of [[https://en.wikipedia.org/w/index.php?title=Ernest_Madu&oldid=820863993|820863993]]. We need to add a new checkbox (perhaps checked by default) in the Special:Undelete interface saying "Reset parent ids" or something similar to mimic the old behavior.