When a package has changed SLOTs during time, revdep-rebuild cannot recognize whether the old SLOT exists any longer and tries to emerge the package using the old SLOT found in /var/db/pkg/category/package/SLOT file. Reproducible: Always Steps to Reproduce: 1. emerge a package with no SLOT 2. change package SLOTs to something not containing SLOT 0 3. remove a library that the package depends on 4. run revdep-rebuild Actual Results: For example, kdevelop used to have only SLOT 0. It now has 3 SLOTS (3, 3.5 and 4) but no SLOT 0. So if for a reason kdevelop breaks, the revdep-rebuild tool tries to emerge dev-util/kdevelop:0 which no longer exists. * All prepared. Starting rebuild emerge --oneshot dev-util/kdevelop:0 .......... These are the packages that would be merged, in order: Calculating dependencies... done! emerge: there are no ebuilds to satisfy "dev-util/kdevelop:0". Expected Results: revdep-rebuild could implement a SLOT checking feature for non-existing SLOTS and provide a mechanism for SLOT migration.
Without a slotmove in /usr/portage/profiles/updates, there is really no way that revdep-rebuild can handle this situation in an automatic fashion. I would rather leave it as is where it errors out and the administrator of the system chooses what to do to fix the system.