Python 3 preparation: "raise" syntax. Changing "raise Exception, value" to "raise Exception(value)". Tool-assisted patch. Particular cases to check carefully are the one place in frontends/ZRoundup/ZRoundup.py where a string exception needed to be fixed, and the one in roundup/cgi/client.py involving raising an exception with a traceback (requires three-argument form of raise in Python 2, which as I understand it requires exec() to avoid a Python 3 syntax error).