Comment 3 for bug 353805

Easier reproducer without external file:

>>> b=lp.bugs[89040]
>>> b.addAttachment(comment='', data='"]\xb6"\n', description='test353805', filename='test353805', is_patch=False)

I work around this with

  data=report['Stacktrace'].decode('UTF-8', 'replace')

for now, but I'd like to revert this soon, since it is destructive.