$ git clone -n https://github.com/xcp-ng-rpms/gnutls.git /var/lib/mock/v8.3-incoming-11600-29895/root/chroot_tmpdir/scmroot/gnutls
Cloning into '/var/lib/mock/v8.3-incoming-11600-29895/root/chroot_tmpdir/scmroot/gnutls'...
$ git fetch origin 13e28a31fbf07200f73905b77ed3a50792d5f1b6:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/gnutls
 * [new ref]         13e28a31fbf07200f73905b77ed3a50792d5f1b6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 13e28a3 Merge branch 'XS-8.3' into "8.3"