Initial Patch by arfrever.
* Issue 89: added a side bar with a download link to the doc.
* Issue 86: fixed missing sentence in pkg_resources doc.
+* Added a nicer error message when a DistributionNotFound is raised.
env = Environment(self.entries)
dist = best[req.key] = env.best_match(req, self, installer)
- raise DistributionNotFound(req) # XXX put more info here
+ msg = ("The '%s' distribution was not found on this "
+ "system, and is required by this application.")
+ raise DistributionNotFound(msg % req)
# Oops, the "best" so far conflicts with a dependency