In [[https://www.mediawiki.org/wiki/MediaWiki_1.25 | MediaWiki 1.25 ]] there was an API change [[https://lists.wikimedia.org/pipermail/mediawiki-api-announce/2014-November/000073.html | announced]]:
list=deletedrevs becomes list=alldeletedrevisions
prop=deletedrevs becomes prop=deletedrevisions
http://git.wikimedia.org/blobdiff/mediawiki%2Fcore.git/991de897e4781597f60a9c19d84df740a2b68ed1/includes%2Fapi%2FApiQueryDeletedrevs.php
`APISite.deletedrevs` uses API `deletedrevs`. This should use list `alldeletedrevisions` or prop `deletedrevisions` on 1.25+ (See APISite.version). The version test could be more specific. i.e. if it was released in `1.25wmf7` (as announced, but may not be reality), that can be used as the version test.
pywikibot/data/api.py includes a TODO which can be removed when this is completed.
See also {T74733}.