$ git clone -n https://src.fedoraproject.org/rpms/nettle.git /var/lib/mock/f42-build-side-1-3498645-45963/root/chroot_tmpdir/scmroot/nettle
Cloning into '/var/lib/mock/f42-build-side-1-3498645-45963/root/chroot_tmpdir/scmroot/nettle'...
$ git fetch origin 79c6dd3213b9e594932cef75a3bad5fbd2237378:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/nettle
 * [new ref]         79c6dd3213b9e594932cef75a3bad5fbd2237378 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 79c6dd3 Update to nettle 3.10.1