$ git clone -n https://src.fedoraproject.org/rpms/rust-object0.37.git /var/lib/mock/f45-build-43500-803/root/chroot_tmpdir/scmroot/rust-object0.37
Cloning into '/var/lib/mock/f45-build-43500-803/root/chroot_tmpdir/scmroot/rust-object0.37'...
$ git fetch origin 21b421de182493db928acf0d0374ba5b2c8258b7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-object0.37
 * [new ref]         21b421de182493db928acf0d0374ba5b2c8258b7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 21b421d Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild