$ git clone -n https://src.fedoraproject.org/rpms/rust-serde_with.git /var/lib/mock/f41-build-1197919-22358/root/chroot_tmpdir/scmroot/rust-serde_with
Cloning into '/var/lib/mock/f41-build-1197919-22358/root/chroot_tmpdir/scmroot/rust-serde_with'...
$ git fetch origin aa6e0352063dc3344e72935df489910efd18dd9a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-serde_with
 * [new ref]         aa6e0352063dc3344e72935df489910efd18dd9a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at aa6e035 Update to version 3.8.1; Fixes RHBZ#2269076