Some comments about shutil.diff:

1) This seems to be against 2.5. You would be better off submitting a
patch against trunk. In case of bug fixes, it will usually be back
ported. This particular change is not a bug fix though.

2) patches should be either context diff or preferably unified diffs. In
addition, a patch should be a forward diff (diff <original file>
<changed file>. It is best to simply do "svn diff".

3) Now for the actual content of the patch, it must be noted that
ignoring WindowsError in copy2 breaks compatibility. Not that there is
any reason for any one to be depending on it, but I just thought I would
point it out. In any case, it will require slight doc change. 

Lastly, just to be clear, the original problem reported in this bug
would still remain.