Persistent error message about py extensions.

[Guillermo Espertino (Gez)]

Ubuntu 9.04 - 64 bits
Inkscape 0.47 Pre1 (previous pre-releases and development builds too)
Genius Pensketch Graphic Tablet (wizardpen driver).

I'm getting this error very frequently. I assume it's somehow related to the tablet because I never saw it in another machine with similar hardware and no tablet. I even installed the new version of the system from scratch, and the bug is still there (I seen it in Ubuntu 8.10 for the first time, and it's still there after a clean 9.04 installation)

The error pops up, and no matter how many times you close it, it pops up again, leaving no remedy than closing inkscape.
The error pops up randomly, posibly more frequently after copy and paste from another session, but I can't find a reliable way to reproduce it.
Anyway it's very frequent. It seems to appear less frequently when I restart the machine, and more frequently once it appeared.
The error seems to point about something related to py extensions, but as far as I know, the error appear during procedures completely unrelated to those extensions.

Here's the error message:

No matching node for expression: /svg:svg/@sodipodi:docname
Traceback (most recent call last):
  File "/usr/share/inkscape/extensions/gimp_xcf.py", line 173, in <module>
    e.affect()
  File "/usr/share/inkscape/extensions/inkex.py", line 198, in affect
    self.effect()
  File "/usr/share/inkscape/extensions/gimp_xcf.py", line 37, in effect
    docname = self.xpathSingle('/svg:svg/@sodipodi:docname')[:-4]
TypeError: 'NoneType' object is unsubscriptable

[su_v (suv-lp)]

duplicate of bug #347987? ;-)

[Guillermo Espertino (Gez) (gespertino-gmail)]

~suv:
Yes and no. :-)
I marked that bug as fixed because apparently the cleaning of the preferences fixed it, but the bug came back in short time.
I wanted to re-open it, but I lost the bug number and the launchpad system is stupid enough to don't let me find it even use the search function, so I opened a new report...

Well, I'm marking this as a duplicate and I'll follow in the original report.