$ git clone -n https://github.com/xcp-ng-rpms/xen /var/lib/mock/v8.3-incoming-8837-27777/root/chroot_tmpdir/scmroot/xen
Cloning into '/var/lib/mock/v8.3-incoming-8837-27777/root/chroot_tmpdir/scmroot/xen'...
$ git fetch origin 305de580ca51f409ab207a4ac390c97d1bf72dfa:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xen
 * [new ref]         305de580ca51f409ab207a4ac390c97d1bf72dfa -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 305de58 Merge branch 'XS-8.3' into 8.3-rebase-XS-20250709