$ git clone -n https://src.fedoraproject.org/rpms/rust-prost-derive0.10.git /var/lib/mock/f42-build-side-1-3502545-45978/root/chroot_tmpdir/scmroot/rust-prost-derive0.10
Cloning into '/var/lib/mock/f42-build-side-1-3502545-45978/root/chroot_tmpdir/scmroot/rust-prost-derive0.10'...
$ git fetch origin 8ff9a9187e2d7fd26d1e422cf63c9af7600c46f1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-prost-derive0.10
 * [new ref]         8ff9a9187e2d7fd26d1e422cf63c9af7600c46f1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8ff9a91 compat package no longer needed