title: Can entry points be used without installation?
body: <p>I've been looking into entry points, but I didn't manage to find whether they <em>required</em> installation into an environment (virtual or not) to be discoverable.</p>
  
  <p>Requiring installation would be inconvenient when working on both base and extensions of a system with potentially lots of extensions. For instance Mercurial would be inconvenient if working on an extension required installing it, or if the "builtin" extensions had to be installed separately to be visible.</p>