$ git clone -n https://src.fedoraproject.org/rpms/R-BufferedMatrix.git /var/lib/mock/f45-build-5885-345/root/chroot_tmpdir/scmroot/R-BufferedMatrix
Cloning into '/var/lib/mock/f45-build-5885-345/root/chroot_tmpdir/scmroot/R-BufferedMatrix'...
$ git fetch origin 4685ec9b477b7a19441caaeb3ce7ce15dad49bc2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-BufferedMatrix
 * [new ref]         4685ec9b477b7a19441caaeb3ce7ce15dad49bc2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4685ec9 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild