$ git clone -n https://src.fedoraproject.org/rpms/rust-startup-disk.git /var/lib/mock/f42-build-3304387-41426/root/chroot_tmpdir/scmroot/rust-startup-disk
Cloning into '/var/lib/mock/f42-build-3304387-41426/root/chroot_tmpdir/scmroot/rust-startup-disk'...
$ git fetch origin 91f055d0376e73dc292b178925c97b436eac9021:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-startup-disk
 * [new ref]         91f055d0376e73dc292b178925c97b436eac9021 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 91f055d Update to 0.1.5