Description of problem:
Current version of sievelib is Python 3 compatibile.
Package python3-sievelib is not generated.

$ sudo pip3 install sievelib
You are using pip version 6.0.8, however version 7.0.3 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
Collecting sievelib
  Downloading sievelib-0.8.tar.gz
Installing collected packages: sievelib
  Running setup.py install for sievelib
Successfully installed sievelib-0.8
$ python3 -c 'import sievelib' && echo 'ok'
ok