$ git clone -n https://src.fedoraproject.org/rpms/libe-book.git /var/lib/mock/f45-build-16082-481/root/chroot_tmpdir/scmroot/libe-book
Cloning into '/var/lib/mock/f45-build-16082-481/root/chroot_tmpdir/scmroot/libe-book'...
$ git fetch origin 6b59ab9e2760814fc0584dccb4911831bd4971e6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libe-book
 * [new ref]         6b59ab9e2760814fc0584dccb4911831bd4971e6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6b59ab9 Update to a new upstream release