$ git clone -n https://src.fedoraproject.org/rpms/rust-darling_macro.git /var/lib/mock/f38-build-side-43-rust-devel-1397676-31053/root/chroot_tmpdir/scmroot/rust-darling_macro
Cloning into '/var/lib/mock/f38-build-side-43-rust-devel-1397676-31053/root/chroot_tmpdir/scmroot/rust-darling_macro'...
$ git fetch origin 838a2f962448fc1e92a267eecc93968149a0f663:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-darling_macro
 * [new ref]         838a2f962448fc1e92a267eecc93968149a0f663 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 838a2f9 Update to version 0.20.3; Fixes RHBZ#2190305