$ git clone -n https://src.fedoraproject.org/rpms/rust-xxhash-rust.git /var/lib/mock/f45-build-46230-832/root/chroot_tmpdir/scmroot/rust-xxhash-rust
Cloning into '/var/lib/mock/f45-build-46230-832/root/chroot_tmpdir/scmroot/rust-xxhash-rust'...
$ git fetch origin 2427fb361923d72d779bc49ccf9f031795e0a59c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-xxhash-rust
 * [new ref]         2427fb361923d72d779bc49ccf9f031795e0a59c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2427fb3 Update to version 0.8.18; Fixes RHBZ#2500801