$ git clone -n https://github.com/xcp-ng-rpms/libidn2.git /var/lib/mock/v8.3-u-pcoval2-11070-29508/root/chroot_tmpdir/scmroot/libidn2
Cloning into '/var/lib/mock/v8.3-u-pcoval2-11070-29508/root/chroot_tmpdir/scmroot/libidn2'...
$ git fetch origin 6d66a831e753a187fb5be59ec09acd70edb21ff1:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/libidn2
 * [new ref]         6d66a831e753a187fb5be59ec09acd70edb21ff1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6d66a83 bump release for test build