git.gnome.org is no more. It has ceased to be. It's an ex-git.
Please see here:
https://about.gitlab.com/2018/05/31/welcome-gnome-to-gitlab/
Note that gitlab does not support git://, only https:// (and ssh).
[Commit message from Alexander Kanavin]
(From OE-Core rev: 8382cdc0888ca645a44aacaac1155afb8dcde979)
(From OE-Core rev: d40c87b003b290a1739039156b27f194f68f12c2)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
[Fixup for sumo context]
Signed-off-by: Armin Kuster <akuster808@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>