I've posted a new Quicklisp client. You can get it with (ql:update-client), and it will take effect after a restart. It changes how local projects are found.
Local projects no longer take precedence over all other system search mechanisms. The local project directory ~/quicklisp/local-projects/ is checked after the ASDF source registry but before the Quicklisp dist mechanism. That means you can override Quicklisp systems, either local project systems or dist software systems, by managing your ASDF central registry appropriately.
This change is in response to user feedback. If you run into any problems with the local project mechanism, which is still evolving, please let me know!