It's not necessary for it to do that, since OWNED BY requires only ordinary
catalog updates and doesn't affect future sequence values.  And pg_upgrade
needs to use OWNED BY without having it change the sequence's relfilenode.
Commit 3d79013b broke this by making all forms of ALTER SEQUENCE change
the relfilenode; that seems to be the explanation for the hard-to-reproduce
buildfarm failures we've been seeing since then.

Discussion: https://postgr.es/m/19785.1497215827@sss.pgh.pa.us