$ git clone -n https://github.com/xcp-ng-rpms/xs-opam-repo.git /var/lib/mock/v8.3-u-asultanov2-9679-28401/root/chroot_tmpdir/scmroot/xs-opam-repo
Cloning into '/var/lib/mock/v8.3-u-asultanov2-9679-28401/root/chroot_tmpdir/scmroot/xs-opam-repo'...
$ git fetch origin e4b251bbadcb1d94b9cc5077bf0c2bb20907369a:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xs-opam-repo
 * [new ref]         e4b251bbadcb1d94b9cc5077bf0c2bb20907369a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e4b251b bump release for test build