...
ceph was not in my list, because it isn't returned by the first query
shown at https://fedoraproject.org/wiki/Changes/F33Boost173#Dependencies

Does it actually depend on any libboost_*.so libraries, or just use
the header-only libraries? If it only uses the header-only parts it
doesn't necessarily need to be rebuilt (there won't be broken deps
when the previous boost release gets replaced in the rawhide repo,
although it's possible that other things that link to ceph or that
ceph links to will have been rebuilt, which can cause problems).

Hmm, I do see this in ceph.spec:

BuildRequires:  boost-devel
BuildRequires:  boost-random

But the repoquery doesn't say it needs them.