Guix unable to download from github due to TLS fatal alert

[Mark H Weaver]

I forgot to mention an important problem with the 'magit' package.
  
> +    (source (origin
> +             (method url-fetch)
> +             (uri (string-append 
> "https://github.com/downloads/magit/magit/magit-";
> +                                 version ".tar.gz"))

Guix is currently unable to download the magit tarball.  For now I
worked around it by using 'wget' followed by "guix download
file:///path/to/tarball".

Here's what happens:

--8<---------------cut here---------------start------------->8---
$ guix download https://github.com/downloads/magit/magit/magit-1.2.0.tar.gz
starting download of `guix-file.cszPnB' from 
`https://github.com/downloads/magit/magit/magit-1.2.0.tar.gz'...
following redirection to 
`https://cloud.github.com/downloads/magit/magit/magit-1.2.0.tar.gz'...
ERROR: Throw to key `gnutls-error' with args `(#<gnutls-error-enum A TLS fatal 
alert has been received.> handshake)'.
failed to download "guix-file.cszPnB" from 
"https://github.com/downloads/magit/magit/magit-1.2.0.tar.gz";
guix download: error: 
https://github.com/downloads/magit/magit/magit-1.2.0.tar.gz: download failed
--8<---------------cut here---------------end--------------->8---

      Mark