Projects with .tar.bz2 fail to build

[SteveAyre]

Twisted 17.1.0 has the source code on pypi as a .tar.bz2, but pypi-download only supports .tar.gz files.

pypi.release_urls returns:
[{'has_sig': False, 'upload_time': <DateTime '20170211T09:59:53' at 2202200>, 'comment_text': '', 'python_version': 'cp27', 'url': 'https://pypi.python.org/packages/84/c4/4bede83bd54cc5a8498b1920b55580da0301efebd0a635d34dc79b3d06dc/Twisted-17.1.0-cp27-cp27m-win_amd64.whl', 'md5_digest': '524d0f1483a6a8bf49cd807c9028dea8', 'downloads': 0, 'filename': 'Twisted-17.1.0-cp27-cp27m-win_amd64.whl', 'packagetype': 'bdist_wheel', 'path': '84/c4/4bede83bd54cc5a8498b1920b55580da0301efebd0a635d34dc79b3d06dc/Twisted-17.1.0-cp27-cp27m-win_amd64.whl', 'size': 3143775}, {'has_sig': False, 'upload_time': <DateTime '20170211T09:59:02' at 22022d8>, 'comment_text': '', 'python_version': 'source', 'url': 'https://pypi.python.org/packages/d2/5d/ed5071740be94da625535f4333793d6fd238f9012f0fee189d0c5d00bd74/Twisted-17.1.0.tar.bz2', 'md5_digest': '5b4b9ea5a480bec9c1449ffb57b2052a', 'downloads': 0, 'filename': 'Twisted-17.1.0.tar.bz2', 'packagetype': 'sdist', 'path': 'd2/5d/ed5071740be94da625535f4333793d6fd238f9012f0fee189d0c5d00bd74/Twisted-17.1.0.tar.bz2', 'size': 2997334}]

The resulting error is:
ValueError: PYPI returned unsafe url: ''