$ git clone -n https://src.fedoraproject.org/rpms/rust-zstd-sys.git /var/lib/mock/f42-build-side-1-3541410-46580/root/chroot_tmpdir/scmroot/rust-zstd-sys
Cloning into '/var/lib/mock/f42-build-side-1-3541410-46580/root/chroot_tmpdir/scmroot/rust-zstd-sys'...
$ git fetch origin 1b1955abb5494d57ab4eb42d2ac2459069a0bd31:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-zstd-sys
 * [new ref]         1b1955abb5494d57ab4eb42d2ac2459069a0bd31 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1b1955a Update to version 2.0.15+zstd.1.5.7; Fixes RHBZ#2346935