Using the same code example as above, I added a simple print statement in the set method being defined in the defproperty and it fired correctly for -

a.childNodes[0].attributes='something'
**My print statement:**in defproperty set for name: attributes
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/urjit/code/mercurial/python/cpython/Lib/xml/dom/minicompat.py", line 106, in set
    "attempt to modify read-only attribute " + repr(name))
xml.dom.NoModificationAllowedErr: attempt to modify read-only attribute 'attributes'

The getter seems to work fine for localName but the setter somehow does not fire.

I have a fix for this but when I am running the test on my ubuntu vm, it doesnt go beyond test_sndhdr. However, when I run that test directly, it is successful. I can submit a patch if this problem is fixed.