Griffith does not start (Python import exception)

Linux Mint Qiana on Ubuntu Trusty thar base.

~ > lsb_release -rd
Description: Linux Mint 17 Qiana
Release: 17

~ > apt-cache policy griffith
griffith:
  Installiert: 0.13-3
  Installationskandidat: 0.13-3
  Versionstabelle:
 *** 0.13-3 0
        500 http://ftp.tu-chemnitz.de/pub/linux/ubuntu/ trusty/universe i386 Packages
        100 /var/lib/dpkg/status

~ > griffith
Traceback (most recent call last):
  File "/usr/bin/griffith", line 86, in <module>
    import add
  File "/usr/share/griffith/lib/add.py", line 31, in <module>
    import quick_filter
  File "/usr/share/griffith/lib/quick_filter.py", line 25, in <module>
    import db
  File "/usr/share/griffith/lib/db/__init__.py", line 30, in <module>
    from _objects import *
  File "/usr/share/griffith/lib/db/_objects.py", line 33, in <module>
    import validators
  File "/usr/share/griffith/lib/db/validators.py", line 26, in <module>
    from sqlalchemy.orm.interfaces import AttributeExtension, InstrumentationManager

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: griffith 0.13-3
ProcVersionSignature: Ubuntu 3.13.0-24.47-generic 3.13.9
Uname: Linux 3.13.0-24-generic i686
ApportVersion: 2.14.1-0ubuntu3.6
Architecture: i386
CurrentDesktop: KDE
Date: Thu Dec 4 15:11:59 2014
InstallationDate: Installed on 2014-06-25 (161 days ago)
InstallationMedia: Linux Mint 17 "Qiana" - Release i386 20140619
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: griffith
UpgradeStatus: No upgrade log present (probably fresh install)