$ git clone -n https://src.fedoraproject.org/rpms/rust-serde_with_macros.git /var/lib/mock/f40-build-2039549-48278/root/chroot_tmpdir/scmroot/rust-serde_with_macros
Cloning into '/var/lib/mock/f40-build-2039549-48278/root/chroot_tmpdir/scmroot/rust-serde_with_macros'...
$ git fetch origin 36e677fde3b7bf381fb3bdd04b08c6920fb07a41:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-serde_with_macros
 * [new ref]         36e677fde3b7bf381fb3bdd04b08c6920fb07a41 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 36e677f Update to version 3.4.0; Fixes RHBZ#2073000