$ git clone -n https://src.fedoraproject.org/rpms/rust-jobserver.git /var/lib/mock/f40-build-1505231-23885/root/chroot_tmpdir/scmroot/rust-jobserver
Cloning into '/var/lib/mock/f40-build-1505231-23885/root/chroot_tmpdir/scmroot/rust-jobserver'...
$ git fetch origin 84b4e84a1d1a1739c608ba5ad66b9ff6a8cef2e6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-jobserver
 * [new ref]         84b4e84a1d1a1739c608ba5ad66b9ff6a8cef2e6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 84b4e84 Update to version 0.1.31; Fixes RHBZ#2276463