Set status properly on end

Fixes #357

Author: ocelotl

Diff for: opentelemetry-sdk/src/opentelemetry/sdk/trace/__init__.py

@@ -259,14 +259,15 @@ def end(self, end_time: Optional[int] = None) -> None:
                 raise RuntimeError("Calling end() on a not started span.")
             has_ended = self.end_time is not None
             if not has_ended:
+                if self.status is None:
+                    self.status = Status(canonical_code=StatusCanonicalCode.OK)
+
                 self.end_time = end_time if end_time is not None else time_ns()
+
         if has_ended:
             logger.warning("Calling end() on an ended span.")
             return
 
-        if self.status is None:
-            self.set_status(Status(canonical_code=StatusCanonicalCode.OK))
-
         self.span_processor.on_end(self)
 
     def update_name(self, name: str) -> None:

Diff for: opentelemetry-sdk/tests/trace/test_trace.py

@@ -574,7 +574,10 @@ def test_ended_span(self):
                 "Test description",
             )
             root.set_status(new_status)
-            self.assertIs(root.status, None)
+            self.assertEqual(
+                root.status.canonical_code,
+                trace_api.status.StatusCanonicalCode.OK,
+            )
 
     def test_error_status(self):
         try: