$ git clone -n https://src.fedoraproject.org/rpms/rust-vergen.git /var/lib/mock/f40-build-1466264-23684/root/chroot_tmpdir/scmroot/rust-vergen
Cloning into '/var/lib/mock/f40-build-1466264-23684/root/chroot_tmpdir/scmroot/rust-vergen'...
$ git fetch origin 63fa9263d0ff7cfe00735708a817de87b9fdd19a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-vergen
 * [new ref]         63fa9263d0ff7cfe00735708a817de87b9fdd19a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 63fa926 Update gix dependency to 0.63