$ git clone -n https://src.fedoraproject.org/rpms/rubygem-rmagick.git /var/lib/mock/f40-build-2639301-66352/root/chroot_tmpdir/scmroot/rubygem-rmagick
Cloning into '/var/lib/mock/f40-build-2639301-66352/root/chroot_tmpdir/scmroot/rubygem-rmagick'...
$ git fetch origin 327c8e52dd0bb022442e408706e5da502b075da8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-rmagick
 * [new ref]         327c8e52dd0bb022442e408706e5da502b075da8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 327c8e5 5.4.4