[mod_python] DbmSession with gdbm

Has anyone had any success using mod_python with gdbm?  What do you
specify as your dbtype on your session init?  I've tried a number of
combinations, without success, such as:

sess =
Session.DbmSession(req,'/var/www/html2/mp_sess.dbm',None,None,'gdbm',0,0
)

Which results in:

<pre>
Mod_python error: "PythonHandler ddcServer3"

Traceback (most recent call last):

  File "/usr/local/lib/python2.3/site-packages/mod_python/apache.py",
line 299, in HandlerDispatch
    result = object(req)

  File "/var/www/html2/DDCBrowser/Clink/DDC/ddcServer3.py", line 30, in
handler
    sess.save()

  File "/usr/local/lib/python2.3/site-packages/mod_python/Session.py",
line 204, in save
    self.do_save(dict)

  File "/usr/local/lib/python2.3/site-packages/mod_python/Session.py",
line 327, in do_save
    dbm = self._get_dbm()

  File "/usr/local/lib/python2.3/site-packages/mod_python/Session.py",
line 302, in _get_dbm
    result = self._dbmtype.open(self._dbmfile, 'c')

AttributeError: 'str' object has no attribute 'open'

</pre>