$ git clone -n https://src.fedoraproject.org/rpms/vtk.git /var/lib/mock/f41-build-812287-147783/root/chroot_tmpdir/scmroot/vtk
Cloning into '/var/lib/mock/f41-build-812287-147783/root/chroot_tmpdir/scmroot/vtk'...
$ git fetch origin 6e5de7889d75014601dc2c82b2993e6349cbd129:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/vtk
 * [new ref]         6e5de7889d75014601dc2c82b2993e6349cbd129 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6e5de78 Rebuild (gdal)