File _service of Package opam

<services>
  <service mode="manual" name="tar_scm">
    <param name="filename">opam</param>
    <param name="revision">7c92631391984f698f31ee24f3ae4dc1cd3698ff</param>
    <param name="scm">git</param>
    <param name="submodules">disable</param>
    <param name="url">https://github.com/ocaml/opam.git</param>
    <param name="versionformat">@PARENT_TAG@</param>
    <param name="versionrewrite-pattern">[v]?([^\+]+)(.*)</param>
    <param name="versionrewrite-replacement">\1</param>
  </service>
  <service mode="manual" name="recompress">
    <param name="compression">xz</param>
    <param name="file">*.tar</param>
  </service>
  <service mode="manual" name="set_version"/>
</services>