$ git clone -n https://src.fedoraproject.org/rpms/R-MatrixGenerics.git /var/lib/mock/f40-build-2270162-54793/root/chroot_tmpdir/scmroot/R-MatrixGenerics
Cloning into '/var/lib/mock/f40-build-2270162-54793/root/chroot_tmpdir/scmroot/R-MatrixGenerics'...
$ git fetch origin faabcc7a528bf6d129c7f34c1355e0e1e113c040:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-MatrixGenerics
 * [new ref]         faabcc7a528bf6d129c7f34c1355e0e1e113c040 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at faabcc7 Rebuilt for https://fedoraproject.org/wiki/Fedora_40_Mass_Rebuild