Sometimes we want to rename modules. That's no reason to break user configuration. We have handled this sometimes by keeping a compatibility module that loads the new module, and sometimes we have simply broken configuration compatibility. Dummy modules take up compilation time and add clutter the source tree. I propose a lighter-weight solution: maintain a simple list of deprecated module aliases in the module loading code. If configuration contains a module that is on the list, the module loading code issues a warning and loads the modern version of the module.