Occurred to me while I *wasn't* thinking about it, that there's some benefit to combining the package_update functionality into the entity checker. The entity checker already breaks apart the entities/package file into a package identifier and the name of the tarball or patch file. So all that's really needed is to provide a package_locations file indexed by package identifier that the checker can use to update the source tree.
Maybe I'll code that up, and maybe not...
