Problems with downloading from https

[Alex Kost]

Hello, I noticed <http://debbugs.gnu.org/cgi/bugreport.cgi?bug=18831>
and decided to ask about a similar problem I have.

Whenever I try to download anything from https, I get an error, for
example:

--8<---------------cut here---------------start------------->8---
$ guix download https://savannah.gnu.org/projects/guix/
starting download of `/tmp/guix-file.Z7tZhy' from 
`https://savannah.gnu.org/projects/guix/'...
;;; Failed to autoload make-session in (gnutls):
;;; ERROR: missing interface for module (gnutls)
ERROR: In procedure module-lookup: Unbound variable: make-session
failed to download "/tmp/guix-file.Z7tZhy" from 
"https://savannah.gnu.org/projects/guix/";
guix download: error: https://savannah.gnu.org/projects/guix/: download failed
--8<---------------cut here---------------end--------------->8---

I have a feeling that I'm missing something obvious but I can't figure
it out.  Any help appreciated.

-- 
Thanks,
Alex