$ git clone -n https://src.fedoraproject.org/rpms/rust-serde_stacker.git /var/lib/mock/f39-build-1492898-34533/root/chroot_tmpdir/scmroot/rust-serde_stacker
Cloning into '/var/lib/mock/f39-build-1492898-34533/root/chroot_tmpdir/scmroot/rust-serde_stacker'...
$ git fetch origin eb9cd79af3251a1d24d1826d93fb16fef1ca527c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-serde_stacker
 * [new ref]         eb9cd79af3251a1d24d1826d93fb16fef1ca527c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at eb9cd79 Update to version 0.1.10; Fixes RHBZ#2223144