$ git clone -n https://src.fedoraproject.org/rpms/rust-tokio-timer.git /var/lib/mock/f41-build-side-1-2897338-34638/root/chroot_tmpdir/scmroot/rust-tokio-timer
Cloning into '/var/lib/mock/f41-build-side-1-2897338-34638/root/chroot_tmpdir/scmroot/rust-tokio-timer'...
$ git fetch origin cb4a2c30b4208ff2cc48490661749bd830e68973:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-tokio-timer
 * [new ref]         cb4a2c30b4208ff2cc48490661749bd830e68973 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at cb4a2c3 no longer needed