$ git clone -n https://src.fedoraproject.org/rpms/rust-serde_json.git /var/lib/mock/f40-build-2619478-64605/root/chroot_tmpdir/scmroot/rust-serde_json
Cloning into '/var/lib/mock/f40-build-2619478-64605/root/chroot_tmpdir/scmroot/rust-serde_json'...
$ git fetch origin 02ca29b835e0ac18af1596651065cc685068a85d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-serde_json
 * [new ref]         02ca29b835e0ac18af1596651065cc685068a85d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 02ca29b Update to version 1.0.113; Fixes RHBZ#2260592