$ git clone -n https://src.fedoraproject.org/rpms/rust-nettle-sys.git /var/lib/mock/f39-build-1494012-34542/root/chroot_tmpdir/scmroot/rust-nettle-sys
Cloning into '/var/lib/mock/f39-build-1494012-34542/root/chroot_tmpdir/scmroot/rust-nettle-sys'...
$ git fetch origin 8f94592020c6d316c981a7bb842e55c087862a4e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-nettle-sys
 * [new ref]         8f94592020c6d316c981a7bb842e55c087862a4e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8f94592 Update to version 2.3.0; Fixes RHBZ#2243826