still no luck with it :(
I precede git command by proxychains one since git does not respect any kind of proxy settings (nor system wide or those I set via git config http.proxy) and it only works  in such way.
==============================================================================
ProxyChains-3.1 (http://proxychains.sf.net)
Initialized empty Git repository in /home/teo/prj/archipel/Archipel/Libvirt/.gnulib/.git/
git.sv.gnu.org[0: 140.186.70.72]: errno=Connection refused
fatal: unable to connect a socket (Connection refused)
Clone of 'git://git.sv.gnu.org/gnulib.git' into submodule path '.gnulib' failed
Failed to recurse into submodule path 'Libvirt'
Unable to initialize submodules
==============================================================================

I suspect it still tries to use git proto somehow...

here's the output from another libvirt repo
==============================================================================
time proxychains git clone https://github.com/marcusk/libvirt.git
ProxyChains-3.1 (http://proxychains.sf.net)
Initialized empty Git repository in /home/teo/prj/libvirt/.git/
remote: Counting objects: 50464, done.
remote: Compressing objects: 100% (8268/8268), done.
remote: Total 50464 (delta 42261), reused 50257 (delta 42058)
Receiving objects: 100% (50464/50464), 51.74 MiB | 177 KiB/s, done.
Resolving deltas: 100% (42261/42261), done.

real    7m42.509s
user    0m13.210s
sys     0m1.140s
==============================================================================

2011/1/24 Daniel P. Berrange <berrange@redhat.com>
On Mon, Jan 24, 2011 at 11:33:28PM +1100, Justin Clift wrote:
> On 24/01/2011, at 11:06 PM, Fyodor Kupchik wrote:
> > I can make a checkout from https://github.org and there exist several repos with the libvirt sources but I don't know if I can safely use them.
> >
> > Unfortunately I can't use snapshot since I'm using scripted installation procedure. Yes, I can rewrite the script but it is not convenient to me because I want to automate update and compilation of sources and maintaining the patches for the bootstrap script looks painful to me.
> >
> > Can anyone from the official team create a repo on github server and configure mirroring the sources tree? Of course the best way it to have HTTPS on the official libvirt.org site.
>
> Hey Daniel, where is the git mirroring to gitorious done?
>
> Is it a script or something that pushes from the libvirt.org servers, or something that pulls from gitorious, or something else?
>
> Was thinking of setting up an equivalent for GitHub, as
>  gitorious has problems with http:// and https:// access.

Err, http:// access works fine with gitorious. I think
you simply didn't wait long enough. GIT's  HTTP access
mechanism is seriously inefficient, and doesn't appear
to give you ongoing progress feedback like the git://
protocol, so expect to wait a while. I've verified I
can clone the main GIT repo over http in about 2 minutes
using:

 git clone http://git.gitorious.org/libvirt/libvirt.git

Regards,
Daniel