commit d74f2102a0 added a validation check
to chroot_archives for its 'pass' parameter. this was based upon finding
an instance where the wrong value was being submitted to the script and
wanting to ensure such mistakes would be caught.
unfortunately it seems that I made a mistake in misremembering the facts
surrounding the latter issue when constructing the validation check and
failed to double check with testing until it was already merged. a
correction is needed. the set of valid values is not limited to only
'source|binary' but actually 'source|binary|chroot'. I'd misremembered
'chroot' as being a completely invalid value.