$ git clone -n https://github.com/xcp-ng-rpms/libidn2.git /var/lib/mock/v8.3-u-pcoval1-11069-29506/root/chroot_tmpdir/scmroot/libidn2
Cloning into '/var/lib/mock/v8.3-u-pcoval1-11069-29506/root/chroot_tmpdir/scmroot/libidn2'...
$ git fetch origin b7c9bf2a1d62b0a5e78a46884b78fb5cee7cb18c:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/libidn2
 * [new ref]         b7c9bf2a1d62b0a5e78a46884b78fb5cee7cb18c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b7c9bf2 bump release for test build