$ git clone -n https://src.fedoraproject.org/rpms/rust-below-dump.git /var/lib/mock/f42-build-side-1-3505180-45989/root/chroot_tmpdir/scmroot/rust-below-dump
Cloning into '/var/lib/mock/f42-build-side-1-3505180-45989/root/chroot_tmpdir/scmroot/rust-below-dump'...
$ git fetch origin b41829b26e51c48a6f80ec19c78fe5248dc02a1a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-below-dump
 * [new ref]         b41829b26e51c48a6f80ec19c78fe5248dc02a1a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b41829b Update to 0.9.0; Fixes: RHBZ#2347636