Workaround #1805553 (single disk not selected as install target)
    
    Rawhide seems to have developed a bug where a single disk is no
    longer automatically selected as the install target when you
    enter the INSTALLATION DESTINATION spoke. We need to work around
    this (but register it as a soft failure).
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>