message: reactor.network.HTTPServer: Fix warning.
diff: @@ -300,7 +300,7 @@ namespace elle
  elle::IOStream input(content.istreambuf());
  auto json = elle::json::read(input);
  }
  - catch (elle::json::ParseError)
  + catch (elle::json::ParseError const&)
  {
  throw Exception(cmd.path(),
  reactor::http::StatusCode::Bad_Request,
  