$ git clone -n https://src.fedoraproject.org/rpms/R-combinat.git /var/lib/mock/f45-build-6031-345/root/chroot_tmpdir/scmroot/R-combinat
Cloning into '/var/lib/mock/f45-build-6031-345/root/chroot_tmpdir/scmroot/R-combinat'...
$ git fetch origin f4e90e1df859e14128287c1a0b33391c653f48eb:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-combinat
 * [new ref]         f4e90e1df859e14128287c1a0b33391c653f48eb -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f4e90e1 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild