fix inadequate chroot_archives validation

commit d74f2102 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.