Fail trace propagation.

Author: purple4reina

datadog_lambda/tracing.py

@@ -582,6 +582,7 @@ def extract_dd_trace_context(
     Write the context to a global `dd_trace_context`, so the trace
     can be continued on the outgoing requests with the context injected.
     """
+    return None
     global dd_trace_context
     trace_context_source = None
     event_source = parse_event_source(event)