$ git clone -n https://src.fedoraproject.org/rpms/rust-hex.git /var/lib/mock/f45-build-42320-792/root/chroot_tmpdir/scmroot/rust-hex
Cloning into '/var/lib/mock/f45-build-42320-792/root/chroot_tmpdir/scmroot/rust-hex'...
$ git fetch origin fc48ef57b4e1a41e71503f25250dfb4fa8cdef09:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-hex
 * [new ref]         fc48ef57b4e1a41e71503f25250dfb4fa8cdef09 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at fc48ef5 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild