Failed to track git repo: "Empty reply from server"

Cloning the repo directly with git is ok, but when we try to track it fails:

> bst track bootstrap/build/rsync.bst
[--:--:--] START   bootstrap/build/rsync.bst-0: Tracking master from https://git.samba.org/rsync.git
    Running host command /home/jjardon/freedesktop-sdk/freedesktop-sdk: /usr/bin/git clone --mirror -n https://git.samba.org/rsync.git /home/jjardon/.cache/buildstream/sources/git_tag/tmp3v2wfqm2
    [--:--:--] STATUS  bootstrap/build/rsync.bst-0: Running host command

        /usr/bin/git clone --mirror -n https://git.samba.org/rsync.git /home/jjardon/.cache/buildstream/sources/git_tag/tmp3v2wfqm2
    Cloning into bare repository '/home/jjardon/.cache/buildstream/sources/git_tag/tmp3v2wfqm2'...
    Running host command /home/jjardon/.cache/buildstream/sources/git_tag/https___git_samba_org_rsync_git: /usr/bin/git fetch origin --prune --tags --force
    [--:--:--] STATUS  bootstrap/build/rsync.bst-0: Running host command

        /usr/bin/git fetch origin --prune --tags --force
    fatal: unable to access 'https://git.samba.org/rsync.git/': Empty reply from server
    [00:00:07] FAILURE bootstrap/build/rsync.bst-0: Tracking master from https://git.samba.org/rsync.git
    [00:00:07] FAILURE bootstrap/build/rsync.bst: git_tag source at bootstrap/build/rsync.bst [line 14 column 2]: Failed to fetch from remote git repository: https://git.samba.org/rsync.git
    ======================================================================