When installing a package that requires the dev version of another package, it fails to to and download a dev version of the package. This appears to be because it either searches the filesystem for the prereq version, or asks CheeseShop. Given that the prereq indicates it wants a dev version, it would seem reasonable to search CheeseShop with ==dev equivalent active. As an example, if you install: easy_install -U hellahella==dev It installs fine from svn, then goes back searching for Pylons, and gets: Processing dependencies for hellahella==0.1dev-r576 Searching for Pylons>=0.1dev-r289 Reading http://www.python.org/pypi/Pylons/ Reading http://pylons.groovie.org/ No local packages or download links found for Pylons>=0.1dev-r289 error: Could not find distribution for Requirement.parse ('Pylons>=0.1dev-r289') Yet, if you run: easy_install -U Pylons==dev It has no problem fetching the latest Pylons and the Paste prereqs (which would have the same problem if I hadn't linked to them explicitly on the Pylons page). Since you already indicate you want ==dev, shouldn't it keep that during the prereq if necessary? - Ben