Steps to reproduce:
* Go to Special:Watchlist in the mobile view (e.g. https://fa.m.wikipedia.org/wiki/Special:Watchlist?uselang=en)
* Click on the "diff" link for one of the changes
* It will take you to a URL similar to this one: https://fa.m.wikipedia.org/w/index.php?title=Special:MobileDiff/30145260&curid=5381367&uselang=en (note that both a `curid` and an `oldid` are present)
* What you see will ***not*** be a Diff page. It will be the "View" version of the page.
* Compare with https://fa.m.wikipedia.org/w/index.php?title=Special:MobileDiff/30145260&uselang=en with does not have a `curid` and what you get is an actual diff page.
Of note, the issue with curid confusing what should be rendered is coming up twice now (previously in T260713 where I assumed it was intended behavior, so I revised #CheckUser code to simply not return `curid` when not applicable). Could we have possibly messed up the order in which parameters are consumed such that `curid` is now being checked before others? The issue reported here, with diff links, is certainly new.