Currently links such as https://www.mediawiki.org/wiki/Special:Permalink/1 redirect to https://www.mediawiki.org/w/index.php?oldid=1.
I'm not sure why we redirect to the /w/index.php URL form for this Special page and for Special:Diff. Perhaps we should stop doing that. Or if this is necessary and crucial behavior, we should at least add comments to files such as includes/specials/SpecialPermanentLink.php documenting the design decision's rationale.
Related: T18659: Add short permalink route for revision oldid (e.g. /revision/123).