error: %guix-register-program: unbound variable on guix time-machine

[Maxim Cournoyer <maxim.cournoyer@gmail.com>]

Hello,

Attempting to navigate to a relatively distant past (Wed Jan 25 23:42:11
2017 -0500) with commit 9b9e147117e6009451d7acc1f8f156e041263e32, I hit:

--8<---------------cut here---------------start------------->8---
$ LANG=C guix time-machine --commit=9b9e147117e6009451d7acc1f8f156e041263e32 -- shell --pure -D openconnect autoconf automake libtool
Updating channel 'guix' from Git repository at 'https://git.savannah.gnu.org/git/guix.git'...
Updating channel 'sfl-packages' from Git repository at 'https://gitlab.com/Apteryks/sfl-guix-channel'...
Backtrace:
In guix/store.scm:
   659:37 19 (thunk)
In guix/status.scm:
    839:4 18 (call-with-status-report _ _)
In guix/store.scm:
   1298:8 17 (call-with-build-handler #<procedure 7f9f1de51270 at g?> ?)
  2168:25 16 (run-with-store #<store-connection 256.99 7f9f1ddff4b0> ?)
In guix/inferior.scm:
    927:8 15 (_ _)
In guix/channels.scm:
    975:2 14 (_ _)
    917:2 13 (_ _)
In ./guix/monads.scm:
    487:9 12 (_ _)
In guix/store.scm:
   1996:8 11 (_ _)
In guix/channels.scm:
   793:19 10 (_ _)
In guix/store.scm:
   1996:8  9 (_ _)
In guix/channels.scm:
   668:36  8 (_ #<store-connection 256.99 7f9f1ddff4b0>)
   729:11  7 (_)
In ice-9/eval.scm:
    619:8  6 (_ #(#(#(#<directory (build-self) 7f9f1de8fa00>) # ?) ?))
   626:19  5 (_ #(#(#(#<directory (build-self) 7f9f1de8fa00>) # ?) ?))
    155:9  4 (_ #(#(#(#<directory (build-self) 7f9f1de8fa00>) # ?) ?))
   223:20  3 (proc #(#(#(#<directory (build-self) 7f9f1de8fa00>) ?) ?))
In unknown file:
           2 (%resolve-variable (7 . %guix-register-program) #<direc?>)
In ice-9/boot-9.scm:
  1685:16  1 (raise-exception _ #:continuable? _)
  1685:16  0 (raise-exception _ #:continuable? _)

ice-9/boot-9.scm:1685:16: In procedure raise-exception:
error: %guix-register-program: unbound variable
--8<---------------cut here---------------end--------------->8---

Is this expected?  info '(guix) Invoking guix time-machine' does not
mention of any point "too far" in the past to travel to.

-- 
Thanks,
Maxim