[Distutils] What are non-active development eggs?

I've posted this question to Stackoverflow[1], but didn't get a response there so I thought I'd ask here. (This is simply a copy and paste of that question) For whatever reason, my build system isn't installing one of my packages properly. When I use yolk (from within a virtualenv), I get the following: bin/yolk -l elig elig - 3.1.2.dev - non-active development (/home/jason/src/interface_dev/elig) How exactly does a package go from active development to non-active development? [1] http://stackoverflow.com/questions/3187496/what-does-it-mean-when-a-package-...