Ghc and profile creation bug

[Andreas Enge <andreas@enge.fr>]

Hello,

even after "make distclean; ./configure; make install", I obtain the following
with c833ab5 (and before):

$ guix package -n -u
Backtrace:                                           
In ice-9/boot-9.scm:
 157: 18 [catch #t #<catch-closure 1b09bc0> ...]
In unknown file:
   ?: 17 [apply-smob/1 #<catch-closure 1b09bc0>]
In ice-9/boot-9.scm:
  63: 16 [call-with-prompt prompt0 ...]
In ice-9/eval.scm:
 432: 15 [eval # #]
In ice-9/boot-9.scm:
2401: 14 [save-module-excursion #<procedure 1b26940 at ice-9/boot-9.scm:4045:3 ()>]
4050: 13 [#<procedure 1b26940 at ice-9/boot-9.scm:4045:3 ()>]
1724: 12 [%start-stack load-stack ...]
1729: 11 [#<procedure 1b3dea0 ()>]
In unknown file:
   ?: 10 [primitive-load "/usr/local/bin/guix"]
In guix/ui.scm:
 849: 9 [run-guix-command package "-n" "-u"]
In ice-9/boot-9.scm:
 157: 8 [catch srfi-34 #<procedure 3144980 at guix/ui.scm:221:2 ()> ...]
 157: 7 [catch system-error ...]
In guix/scripts/package.scm:
1002: 6 [#<procedure 3149870 at guix/scripts/package.scm:991:4 ()>]
 837: 5 [process-actions (# # # # ...)]
In guix/store.scm:
 977: 4 [run-with-store # ...]
In guix/profiles.scm:
 523: 3 [#<procedure 3d1ecf0 at guix/profiles.scm:523:2 (state)> #]
 527: 2 [#<procedure 3cf5270 at guix/profiles.scm:523:2 (t-57033)> #]
 411: 1 [ghc-package-cache-file #<<manifest> entries: (# # # # ...)>]
In unknown file:
   ?: 0 [scm-error misc-error #f ...]

ERROR: In procedure scm-error:
ERROR: No variable named ghc in #<interface (gnu packages haskell) 32fc480>

Andreas