$ git clone -n https://src.fedoraproject.org/rpms/rust-y4m.git /var/lib/mock/f45-build-46243-832/root/chroot_tmpdir/scmroot/rust-y4m
Cloning into '/var/lib/mock/f45-build-46243-832/root/chroot_tmpdir/scmroot/rust-y4m'...
$ git fetch origin 7ae2600eefc15e6d608b720371d48f4af03c302d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-y4m
 * [new ref]         7ae2600eefc15e6d608b720371d48f4af03c302d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7ae2600 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild