[rack] Remove deprecation warning on :datadog_rack_request_span (#672)

* [rack] Remove deprecation warning on :datadog_rack_request_span

* Remove call to env.without_datadog_warnings

lib/ddtrace/contrib/rack/middlewares.rb

@@ -62,12 +62,16 @@ def call(env)
           request_span = tracer.trace(Ext::SPAN_REQUEST, trace_options)
           env[RACK_REQUEST_SPAN] = request_span
 
-          # Add deprecation warnings
-          add_deprecation_warnings(env)
-          env.without_datadog_warnings do
-            # TODO: For backwards compatibility; this attribute is deprecated.
-            env[:datadog_rack_request_span] = env[RACK_REQUEST_SPAN]
-          end
+          # TODO: Add deprecation warnings back in
+          # DEV: Some third party Gems will loop over the rack env causing our deprecation
+          #      warnings to be shown even when the user is not accessing them directly
+          #
+          # add_deprecation_warnings(env)
+          # env.without_datadog_warnings do
+          #   # TODO: For backwards compatibility; this attribute is deprecated.
+          #   env[:datadog_rack_request_span] = env[RACK_REQUEST_SPAN]
+          # end
+          env[:datadog_rack_request_span] = env[RACK_REQUEST_SPAN]
 
           # Copy the original env, before the rest of the stack executes.
           # Values may change; we want values before that happens.

spec/ddtrace/contrib/rack/middleware_spec.rb

@@ -55,7 +55,7 @@
         end
 
         it do
-          expect(Datadog::Tracer.log).to have_received(:warn)
+          expect(Datadog::Tracer.log).to_not have_received(:warn)
             .with(/:datadog_rack_request_span/)
         end
       end