Hi Guix,

When trying to run guix package --show with packages from the
(gnu packages ssh) module, such as openssh, guile-ssh, and libssh, I get 
the following stack trace:

$ guix package --show=openssh
Backtrace:
In ice-9/boot-9.scm:
   3014:26 19 (_)
In unknown file:
           18 (primitive-load-path "gnu/packages/gnupg" #<procedure 1…>)
In gnu/packages/gnupg.scm:
      34:0 17 (_)
In ice-9/boot-9.scm:
    2874:4 16 (define-module* _ #:filename _ #:pure _ #:version _ # _ …)
   2887:24 15 (_)
    222:29 14 (map1 _)
    222:29 13 (map1 _)
    222:29 12 (map1 _)
    222:29 11 (map1 _)
    222:29 10 (map1 _)
    222:17  9 (map1 (((gnu packages curl)) ((gnu packages crypto)) # …))
   2800:17  8 (resolve-interface (gnu packages curl) #:select _ #:hide …)
In ice-9/threads.scm:
     390:8  7 (_ _)
In ice-9/boot-9.scm:
   2726:13  6 (_)
In ice-9/threads.scm:
     390:8  5 (_ _)
In ice-9/boot-9.scm:
   2994:20  4 (_)
    2312:4  3 (save-module-excursion _)
   3014:26  2 (_)
In unknown file:
            1 (primitive-load-path "gnu/packages/curl" #<procedure 20…>)
In gnu/packages/curl.scm:
      55:4  0 (_)

gnu/packages/curl.scm:55:4: error: libssh2: unbound variable

$ guix describe
Generation 123  Apr 04 2019 22:02:49    (current)
   guix-at-duke a9674ec
     repository URL: https://gitlab.oit.duke.edu/jackhill/guix-at-duke.git
     branch: master
     commit: a9674ec7b0decac94745c91df886817e2fc8a91b
   guix 54c9d7b
     repository URL: https://git.savannah.gnu.org/git/guix.git
     branch: master
     commit: 54c9d7bb69847c89a7193347f858bb4e9476f7df

To me, the error looks like a missing module import or simmilar, but I 
can't spot it. Perhaps it is something else.

Best,
Jack