$ git clone -n https://src.fedoraproject.org/rpms/rust-serde_bser.git /var/lib/mock/f41-build-side-1-3134916-39764/root/chroot_tmpdir/scmroot/rust-serde_bser
Cloning into '/var/lib/mock/f41-build-side-1-3134916-39764/root/chroot_tmpdir/scmroot/rust-serde_bser'...
$ git fetch origin 99ab7df47ac55db8e5fccd06b3b8b0288fca4913:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-serde_bser
 * [new ref]         99ab7df47ac55db8e5fccd06b3b8b0288fca4913 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 99ab7df unused leaf package for more than two release cycles