When executing this incomplete command:

$ guix system

I expect to get a usage message, instead I get an error:

Backtrace:
In ice-9/boot-9.scm:
 157: 13 [catch #t #<catch-closure 1772780> ...]
In unknown file:
   ?: 12 [apply-smob/1 #<catch-closure 1772780>]
In ice-9/boot-9.scm:
  63: 11 [call-with-prompt prompt0 ...]
In ice-9/eval.scm:
 432: 10 [eval # #]
In ice-9/boot-9.scm:
2401: 9 [save-module-excursion #<procedure 178f940 at
ice-9/boot-9.scm:4045:3 ()>]
4050: 8 [#<procedure 178f940 at ice-9/boot-9.scm:4045:3 ()>]
1724: 7 [%start-stack load-stack ...]
1729: 6 [#<procedure 17a6ea0 ()>]
In unknown file:
   ?: 5 [primitive-load
"/gnu/store/c8nks9ldf1wx6fbv9zmq7v42z4fv2hqp-guix-0.8.3.5d09263/bin/.guix-real"]
In guix/ui.scm:
1066: 4 [run-guix-command system]
In ice-9/boot-9.scm:
 157: 3 [catch srfi-34 #<procedure 39cb060 at guix/ui.scm:392:2 ()> ...]
 157: 2 [catch system-error ...]
In guix/scripts/system.scm:
 527: 1 [#<procedure 39cb080 at guix/scripts/system.scm:526:2 ()>]
In unknown file:
   ?: 0 [car ()]

ERROR: In procedure car:
ERROR: In procedure car: Wrong type (expecting pair): ()

-Steve