As this really desirable?
I realize it is done to avoid instant auto-re-publication, but as it is now, the expiration date is set even if no rules are set up to do auto-publication (and even when in dry-drun mode!). Also, the option to "Set expiration date on retraction" in the controlpanel would seem to control this behavior, but it's really only an option to override any existing expiration date.
What are the thoughts behind the current implementation?
Would it not be a better default to not change plone standard behavior?