So few code breakage is nice.
I also realized that the exec rule is still too string. If the exec statement passes an explicit namespace -- "exec in foo" -- then there shouldn't be any problem, because the executed code can't affect the current namespace. If this form is allowed, the exec errors in xpcom and Zope disappear.
My very personal feeling is that *any* rule on exec just sounds arbitrary (even if motived and acceptable).
regards, Samuele Pedroni.