invalid literal issue

I'm trying to get this running on a new setup (works on my old one). Ubuntu 12.04 x86_64, python 2.7. The error in the log file is:

2012-08-03 23:26:01,414 Trac[loader] ERROR: Skipping "bzr = tracbzr.backend":
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/Trac-1.0dev_r11167-py2.7.egg/trac/loader.py", line 68, in _load_eggs
    entry.load(require=True)
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 1989, in load
    entry = __import__(self.module_name, globals(),globals(), ['__name__'])
  File "/usr/local/lib/python2.7/dist-packages/TracBzr-0.4.2-py2.7.egg/tracbzr/backend.py", line 47, in <module>
    trac_version = (int(trac.__version__[0]), int(trac.__version__[2:4]))
ValueError: invalid literal for int() with base 10: '0d'

It would appear that the second slice operator isn't correct.