$ git clone -n https://src.fedoraproject.org/rpms/rust-darling_core.git /var/lib/mock/f39-build-2338667-59614/root/chroot_tmpdir/scmroot/rust-darling_core
Cloning into '/var/lib/mock/f39-build-2338667-59614/root/chroot_tmpdir/scmroot/rust-darling_core'...
$ git fetch origin b2319147267c0577786c4394d37014932a956bc4:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-darling_core
 * [new ref]         b2319147267c0577786c4394d37014932a956bc4 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b231914 Update to version 0.20.4; Fixes RHBZ#2261840