Overriding default tags

[paddycarey]

I'm trying to override some of the default tags that nginx-opentracing sets using opentracing_tag directives in my location blocks but it doesn't seem to work, is that expected?

I'm running:

Nginx: 1.13.6 (compiled from source)
OS: Ubuntu 16.04
nginx-opentracing: 0.9.0 (binary release)

The location blocks in my config look like so:

  location / {
    <irrelevant config redacted...>

    opentracing_operation_name "$request_method $uri";
    opentracing_tag "resource.name" "/";

    opentracing_tag "http.host" "$client_host";
    opentracing_tag "http.url" "$scheme://$client_host$uri";

    proxy_pass http://upstream;
  }

But when the span is sent I always see the default http.host and http.url tags as defined in the source here: https://github.com/opentracing-contrib/nginx-opentracing/blob/master/opentracing/src/ngx_http_opentracing_module.cpp#L49-L56

If I modify the config to use different tag names then (as below) then they come through fine, but ideally I'd like to use http.host and http.url to allow better consistency between my services.

  location / {
    <irrelevant config redacted...>

    opentracing_operation_name "$request_method $uri";
    opentracing_tag "resource.name" "/";

    opentracing_tag "http.client_host" "$client_host";
    opentracing_tag "http.client_url" "$scheme://$client_host$uri";

    proxy_pass http://upstream;
  }

Is there anything I can do to make this work currently? If not, does this seem like something that's worth a PR to change the behaviour?