$ git clone -n https://src.fedoraproject.org/rpms/rust-build-context.git /var/lib/mock/f38-build-side-43-rust-devel-1418357-31459/root/chroot_tmpdir/scmroot/rust-build-context
Cloning into '/var/lib/mock/f38-build-side-43-rust-devel-1418357-31459/root/chroot_tmpdir/scmroot/rust-build-context'...
$ git fetch origin b038b53bdbc0be1f3ecea580ce7d0ccf28b081e0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-build-context
 * [new ref]         b038b53bdbc0be1f3ecea580ce7d0ccf28b081e0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b038b53 Initial import (#2236540)