$ git clone -n https://github.com/xcp-ng-rpms/xs-opam-repo.git /var/lib/mock/v8.3-u-asultanov2-11371-29675/root/chroot_tmpdir/scmroot/xs-opam-repo
Cloning into '/var/lib/mock/v8.3-u-asultanov2-11371-29675/root/chroot_tmpdir/scmroot/xs-opam-repo'...
$ git fetch origin 10c675b67040a9ebad03c56b500d0db466ef5aab:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xs-opam-repo
 * [new ref]         10c675b67040a9ebad03c56b500d0db466ef5aab -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 10c675b bump release for test build