$ git clone -n https://src.fedoraproject.org/rpms/rust-serde_with.git /var/lib/mock/f40-build-2658017-66917/root/chroot_tmpdir/scmroot/rust-serde_with
Cloning into '/var/lib/mock/f40-build-2658017-66917/root/chroot_tmpdir/scmroot/rust-serde_with'...
$ git fetch origin 0f672b042fa69ef831c7c648455204a364950a07:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-serde_with
 * [new ref]         0f672b042fa69ef831c7c648455204a364950a07 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0f672b0 Update to version 3.6.1; Fixes RHBZ#2262026