Well, reverted to an older version really. :) It was reported that
efibootmgr-0.6.0 was silently failing to actually write the new variables
to EFI, but that 0.5.4 works. I'm currently unable to test this here as I'm
still using DUET UEFI, and changes to the UEFI variables do not persist
between boots. I also added a few patches from Fedora's repo that seem
reasonable to include. The old (newer) version was moved to /testing in
case it might work better for someone.
Thanks to John Yost for the bug report.