bundle2: transmit exception during part generation If an exception is raised during a bundle2 part payload generation it is now recorded in the bundle. If such exception occurs, we capture it, transmit an abort exception through the bundle, cleanly close the current part payload and raise it again. This allow to generate valid bundle even in case of exception so that the consumer does not wait forever for a dead producer. This also allow to raise the exception during unbundling at the exact point it happened during bundling make debugging easier.