$ git clone -n https://src.fedoraproject.org/rpms/rust-libgit2-sys0.13.git /var/lib/mock/f40-build-2652139-66890/root/chroot_tmpdir/scmroot/rust-libgit2-sys0.13
Cloning into '/var/lib/mock/f40-build-2652139-66890/root/chroot_tmpdir/scmroot/rust-libgit2-sys0.13'...
$ git fetch origin 370b25f1492b0d0eb4810b403ffad2347abb37f5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-libgit2-sys0.13
 * [new ref]         370b25f1492b0d0eb4810b403ffad2347abb37f5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 370b25f compat package no longer needed