Currently it's hard to delete resume lists. If all packages from a resume list were reemerged manually, this list still contain them. I suggest addition of a new option "--delete-resume-lists" to emerge.
Also see bug 156536, comment 6.
Er isn't this really the same as the other bug? In any case, if you're that concerned, might I suggest contributing to this:
I am not spamming, but it's just that people expect too much from the package manager; it's job is to decide what you need to emerge in order to get the packages you want running, and to help you keep that system up to date, as well as providing an execution environment conducive to building all kinds of source. UI stuff can be done in scripts if you need automation.
Not sure if there is a possibility to delete stuff from /var/cache/edb/mtimedb.
I don't see a real use case for deleting resume lists: if you don't need them, don't use them. The risk of "accidentally" resuming a wrong operation is rather minimal IMO and not worth the complexity of yet another special case option in emerge. If you can provide a patch for emaint to do it feel free to reopen this.
Created attachment 134097 [details, diff]
Thanks, I changed it a little and renamed it to "cleanresume". It's in svn r8224.