I would like to propose new package python-setuptools-scm.
(Only if Marco wasn't faster)

setuptools_scm extracts Python package versions from git or hg metadata instead of 
declaring them as the version argument or in a SCM managed file.

This package is the new dependency for existing "duplicity" Python package. It prevents 
from upgrading to duplicity version 2.2.2

Thank you,
Libor