$ git clone -n https://github.com/xcp-ng-rpms/xapi.git /var/lib/mock/v8.3-u-asultanov1-8990-27896/root/chroot_tmpdir/scmroot/xapi
Cloning into '/var/lib/mock/v8.3-u-asultanov1-8990-27896/root/chroot_tmpdir/scmroot/xapi'...
$ git fetch origin 1669f7691d8e7df1c56f9c8a60eab9dfa281b575:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xapi
 * [new ref]         1669f7691d8e7df1c56f9c8a60eab9dfa281b575 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1669f76 attempt