When a detector has a serious problem (e.g. I/O Error, division by zero,
etc,) ultimately a DetectorError is raised. This is defined in
cgi/exceptions.py.

Now I got a Detector Error without any message about what was wrong.

Looks like the Detector Error *does* print its parameters with python3
but not with python2, see the test-script below.

Anybody in-the-know can tell us how to correctly define a custom
exception in python2 that prints its parameters?

python3:

>>> from roundup.cgi.exceptions import DetectorError
>>> raise DetectorError ('Bla', 'some html', 'some text')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
roundup.cgi.exceptions.DetectorError: ('Bla', 'some html', 'some text')

python2:
>>> from roundup.cgi.exceptions import DetectorError
>>> raise DetectorError ('Bla', 'some html', 'some text')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
roundup.cgi.exceptions.DetectorError