Comment 17 for bug 527142

Note that dh_makeshlibs -V will only add depends on >= the upstream version the packages are built against.

If the rdeps are NOT rebuilt, then they will stay with the Depends/shlibs they got at the time of their build. So there's still potential for screwup if the lib break ABI moving forward and you don't upload the rdeps subsequently. But it's still less risky than when allowing any combinations because we don't review ABI changes properly.