A quick bisect suggests that that this bug was introduced by commit 0e765f8405c3ec1b428994d3149599a7132ae07b.

https://gerrit.wikimedia.org/r/#/c/7699/

"Show revdel links instead of checkboxes on pages where there is no multiple
log entry revdel form."

1.20wmf4 is live everywhere now so there is no "before" link anymore but I can confirm that this is a regression.

(In reply to comment #2)

1.20wmf4 is live everywhere now

https://pt.wikipedia.org/wiki/Special:Version
still says 1.20wmf3 (d8d5322).

Indeed, non-English Wikipedias are scheduled to switch over tomorrow [1]. Either way, it's definitely a regression, see my comment on the revision linked [2]. Should be a simple fix for someone familiar with flags (i.e. bitwise operations).

[1] http://www.mediawiki.org/wiki/MediaWiki_1.20/Roadmap
[2] https://gerrit.wikimedia.org/r/#/c/7699/

(In reply to comment #3)

(In reply to comment #2)

1.20wmf4 is live everywhere now so there is no "before" link anymore but I can
confirm that this is a regression.

https://pt.wikipedia.org/wiki/Special:Version
still says 1.20wmf3 (d8d5322).

Yeah, I must have looked somewhere else. But the comment was mostly to clarify the tag and milestone changes.

If this is fixed before next monday we can backport it to 1.20wmf4, other wise it'll happen as part of the 1.20wmf5 roll-out that starts next week.

Fixed in https://gerrit.wikimedia.org/r/#/c/10288/ and deployed.

Awesome!

Oops, sorry about causing that problem.