bug#33100: [libssh] fatal: dumb http transport does not support shallow capabilities

[Maxim Cournoyer <maxim.cournoyer@gmail.com>]

Hello,

Today I stumbled upon libssh that wouldn't build, due to the following
git error:

--8<---------------cut here---------------start------------->8---
fatal: dumb http transport does not support shallow capabilities"
--8<---------------cut here---------------end--------------->8---

There are now substitutes served from Berlin, so it's a bit more
difficult to reproduce, but the following worked for Ludovic and myself:

guix build --check /gnu/store/f0i7bdcg1lksr9dhz0cidi3ym8r8a5wl-libssh-0.7.6-checkout.drv

The output looks like:

--8<---------------cut here---------------start------------->8---
guix build --check /gnu/store/f0i7bdcg1lksr9dhz0cidi3ym8r8a5wl-libssh-0.7.6-checkout.drv
building /gnu/store/f0i7bdcg1lksr9dhz0cidi3ym8r8a5wl-libssh-0.7.6-checkout.drv...
Initialized empty Git repository in /gnu/store/gqyjgpvzqy55dzibm59530fsx21dpiz4-libssh-0.7.6-checkout/.git/
fatal: dumb http transport does not support shallow capabilities
--8<---------------cut here---------------end--------------->8---

Leo, would you have an idea?

Thanks,

Maxim