Sorry, for delay with my answer.
> I'm not sure I see the whole picture yet, but I guess that > > 1) elpa-f in stretch depends on s-el (instead of elpa-s) > 2) elpa-vimish-fold in buster is a new style dh_elpa using package > that only looks at elpa packages for depends. > > Maybe an explicit depends on elpa-s by elpa-vimish-fold would help? Since vimish-fold do not depend on s directly (but f does, and vimish-fold depends on f) this bug concerns rather f, not vimish-fold. But I agree that probably it is easier to explicitly add elpa-s as a dependency of vimish-fold. I can upload an updated package if there are no objections or other proposals. Regards, Lev