Using a clean environment (virtual or not), it is not possible to install pagure.io with pip install.

The setup.py script import pagure to get the _version_ number. But pagure/_init_.py import pagure dependencies. But dependencies have to be installed before (by pip). But pip import setup.py. But the setup.py import ...

How to reproduce:

$ mkdir /tmp/test
$ virtualenv /tmp/test
$ . /tmp/test/bin/activate
$ cd pagure/directory
$ pip install .

_version_ constant should be defined in a separate file that doesn't include pagure dependencies.