$ git clone -n https://src.fedoraproject.org/rpms/rust-rusty-fork.git /var/lib/mock/f45-build-44623-815/root/chroot_tmpdir/scmroot/rust-rusty-fork
Cloning into '/var/lib/mock/f45-build-44623-815/root/chroot_tmpdir/scmroot/rust-rusty-fork'...
$ git fetch origin 89c168532131181869d49b20fe221bbe4d6ec2c3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-rusty-fork
 * [new ref]         89c168532131181869d49b20fe221bbe4d6ec2c3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 89c1685 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild