There are times when one wants to recompile packages not listed in the worldfile (and that is because they were originally emerged as dependencies). Doing that, however, updates the worldfile with the result that those packages won't ever be catched by a depclean. Adding a "do-not-touch-worldfile" commad line switch to emerge would fix that. Reproducible: Always Steps to Reproduce: 1. 2. 3.
emerge --oneshot :)