Martin Pool has voted comment. Status is now: Superseded Comment: I see some risk that this will encourage people to write isinstance(e, InternalBzrError) when they ought to check .internal_error, but not enough to object to this. For details, see: http://bundlebuggy.aaronbentley.com/request/%3C1190940711.17384.1.camel%40lifeless-64%3E