[XML-SIG] problems with PyXML 0.6.3

[Radestock, Guenter]

>     I had 2 tests fail:
>     test test_sax crashed --
>         exception.SystemError : 'finally' pops bad exception
>     test test_saxdrivers crashed --
>         exceptions.IOError : [Errno url error] unknown url type: 'c'

The first is the same problem I tried to reproduce yesterday.  It
happens only on Windows NT or Windows 2000 with the installed
XML package.  I only wish I had some time to look into the coding
(I will try).  Downgrading to an older version of the expat extension
may help; the one supplied with Python2.0 does not have the problem.

The problem is whenever you parse incorrect XML, Python may crash,
instead of just raising an exception (very unfortunate e.g. in an
http server process).