$ git clone -n https://src.fedoraproject.org/rpms/rust-serde-untagged.git /var/lib/mock/f40-build-2269472-54770/root/chroot_tmpdir/scmroot/rust-serde-untagged
Cloning into '/var/lib/mock/f40-build-2269472-54770/root/chroot_tmpdir/scmroot/rust-serde-untagged'...
$ git fetch origin 663fed142a3457f5909b9f3ba1b467b74efffa9a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-serde-untagged
 * [new ref]         663fed142a3457f5909b9f3ba1b467b74efffa9a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 663fed1 Update to version 0.1.5; Fixes RHBZ#2256501