$ git clone -n https://src.fedoraproject.org/rpms/rust-darling.git /var/lib/mock/f40-build-2640586-66405/root/chroot_tmpdir/scmroot/rust-darling
Cloning into '/var/lib/mock/f40-build-2640586-66405/root/chroot_tmpdir/scmroot/rust-darling'...
$ git fetch origin 76a6e0cf2e2d7b704a27dd4b64ba663340a7485d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-darling
 * [new ref]         76a6e0cf2e2d7b704a27dd4b64ba663340a7485d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 76a6e0c Update to version 0.20.8; Fixes RHBZ#2262037