There is no 32-bit base image for Fedora 23. We use virt-builder to create images for upgrade testing in openQA; to test upgrades of 32-bit installs we need to be able to create a 32-bit base image. Could you please add one to the set of base images available for virt-builder?
Really a duplicate of this long-standing Fedora infrastructure feature request: https://fedorahosted.org/rel-eng/ticket/5805
Fixed in https://github.com/libguestfs/libguestfs/commit/0339b3d7a5c7707abbf4b6e4b714733fc8c52a79 It will be uploaded soon.