Enable Revision-Slider on pl.wikipedia as a BetaFeature.
Change 302690 had a related patch set uploaded (by Addshore):
DNM: Enable RevisionSlider on plwiki
@Addshore is going to deploy the RevisionSlider as a beta feature tonight, in the early hours of Thursday
Change 302690 merged by jenkins-bot:
Enable RevisionSlider on plwiki
Mentioned in SAL [2016-08-03T23:19:36Z] <dereckson@tin> Synchronized wmf-config/InitialiseSettings.php: Enable RevisionSlider on plwiki (T141974) (duration: 00m 26s)
This is now deployed on plwiki and working, although the extension will be getting an update (with bug fixes) this evening!