I think Google uses JGit for their public facing Git servers, but I'm not sure.

On February 12, 2018 5:59:50 PM EST, Danny Milosavljevic <dannym@scratchpost.org> wrote:
>Hi Leo,
>
>On Mon, 12 Feb 2018 10:09:39 -0500
>Leo Famulari <leo@famulari.name> wrote:
>
>> I think it's worth adding, but as an option, because there are Git
>> server implementations, like JGit, that don't support shallow
>cloning.
>
>Thanks for that!  I didn't consider that before...
>
>Possible patch (do you know such servers and can test whether they
>still work?):
>
>diff --git a/guix/build/git.scm b/guix/build/git.scm
>index c1af545a7..e54d92be7 100644
>--- a/guix/build/git.scm
>+++ b/guix/build/git.scm
>@@ -37,12 +37,18 @@ recursively.  Return #t on success, #f otherwise."
>   ;; in advance anyway.
>   (setenv "GIT_SSL_NO_VERIFY" "true")
> 
>+  (mkdir-p directory)
>+
>;; We cannot use "git clone --recursive" since the following "git
>checkout"
>   ;; effectively removes sub-module checkouts as of Git 2.6.3.
>-  (and (zero? (system* git-command "clone" url directory))
>+  (and ;(zero? (system* git-command "clone" url directory))
>        (with-directory-excursion directory
>-         (system* git-command "tag" "-l")
>-         (and (zero? (system* git-command "checkout" commit))
>+         ;(system* git-command "tag" "-l")
>+         (invoke git-command "init")
>+         (invoke git-command "remote" "add" "origin" url)
>+         (and (or (zero? (system* git-command "fetch" "--depth" "1"
>"origin" commit))
>+                  (zero? (system* git-command "fetch" "origin"
>commit)))
>+              (zero? (system* git-command "checkout" "FETCH_HEAD"))
>               (begin
>                 (when recursive?
>                   ;; Now is the time to fetch sub-modules.