What it does?
According to ticket phab:T10956, it implements the functionality of indexing deleted pages via ElasticSearch (CirrusSearch extension). This complements indexing usually available for existing pages, so you can now search for partial and unexact matches for the name of the deleted page in Special:Undelete page.
How I test it?
- Go to http://undeltest.wmflabs.org/.
- Create a new page, for example "Mac and Cheese" - be creative and invent your own name though, if everybody will use the same title it would be boring. You may need to fill a captcha when editing - use word "mellon" for it.
- Login as Admin with the password described here: MediaWiki-Vagrant docs at number 7.
- Delete the page you created in (2).
- Go to http://undeltest.wmflabs.org/wiki/Special:Undelete and search for "chease" (note partial and inexact match) - again, be creative with your own title but not too creative - the name should be still close to what you are looking for to be found.
- Observe that the page deleted in (2) is in the list.
What unholy magic is this?
The patches are at:
https://gerrit.wikimedia.org/r/#/c/281078/ (core part)
https://gerrit.wikimedia.org/r/#/c/281077/ (CirrusSearch part)
You are welcome to review/comment.