$ git clone -n https://src.fedoraproject.org/rpms/rust-syn.git /var/lib/mock/f40-build-2643775-66490/root/chroot_tmpdir/scmroot/rust-syn
Cloning into '/var/lib/mock/f40-build-2643775-66490/root/chroot_tmpdir/scmroot/rust-syn'...
$ git fetch origin 7d8ab2b20c20ce09080d63f7c999e4687b1981c6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-syn
 * [new ref]         7d8ab2b20c20ce09080d63f7c999e4687b1981c6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7d8ab2b Update to version 2.0.52; Fixes RHBZ#2265016