$ git clone -n https://src.fedoraproject.org/rpms/rust-nettle-sys.git /var/lib/mock/f45-build-43349-802/root/chroot_tmpdir/scmroot/rust-nettle-sys
Cloning into '/var/lib/mock/f45-build-43349-802/root/chroot_tmpdir/scmroot/rust-nettle-sys'...
$ git fetch origin 3f151d1449b18df85950b85c3a6b4e9be9fdff08:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-nettle-sys
 * [new ref]         3f151d1449b18df85950b85c3a6b4e9be9fdff08 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3f151d1 Build with nettle v3 until the Rust bindings support v4