Error running on RHEL 4?

I tried running the latest code and went as far back as 0.6.07 and I keep getting the following error message when running duplicity.

[root@sierra duplicity]# duplicity
Traceback (most recent call last):
  File "/usr/bin/duplicity", line 42, in ?
    from duplicity import commandline
  File "/usr/lib64/python2.3/site-packages/duplicity/commandline.py", line 147, in ?
    class DupOption(optparse.Option):
  File "/usr/lib64/python2.3/site-packages/duplicity/commandline.py", line 157, in DupOption
    ALWAYS_TYPED_ACTIONS = optparse.Option.ALWAYS_TYPED_ACTIONS + ("extend",)
AttributeError: class Option has no attribute 'ALWAYS_TYPED_ACTIONS'