$ git clone -n https://src.fedoraproject.org/rpms/rust-blake3.git /var/lib/mock/f42-build-side-110548-59020876-6570336/root/chroot_tmpdir/scmroot/rust-blake3
Cloning into '/var/lib/mock/f42-build-side-110548-59020876-6570336/root/chroot_tmpdir/scmroot/rust-blake3'...
$ git fetch origin b0bbbb51c39baef53377bb438d931df4d9eed78a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-blake3
 * [new ref]         b0bbbb51c39baef53377bb438d931df4d9eed78a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b0bbbb5 Update to version 1.8.2; Fixes RHBZ#2361299