If not tracing, don't trace.

Author: pglombardo

instana/instrumentation/urllib3.py

@@ -7,8 +7,13 @@
 
 @wrapt.patch_function_wrapper('urllib3', 'PoolManager.urlopen')
 def urlopen_with_instana(wrapped, instance, args, kwargs):
+    context = instana.internal_tracer.current_context()
+
+    # If we're not tracing, just return
+    if context is None:
+        return wrapped(*args, **kwargs)
+
     try:
-        context = instana.internal_tracer.current_context()
         span = instana.internal_tracer.start_span("urllib3", child_of=context)
         span.set_tag(ext.HTTP_URL, args[1])
         span.set_tag(ext.HTTP_METHOD, args[0])