Address review feedback on S3CopyPrefixOperator

Chain RuntimeError from the original exception to preserve the traceback.
Verify the succeeding object is attempted when continue_on_failure=True.

Author: bentorb

providers/amazon/src/airflow/providers/amazon/aws/operators/s3.py

@@ -506,7 +506,7 @@ def execute(self, context: Context):
                             self.log.error("Failed to copy %s: %s", source_key, e)
                             failed_object_count += 1
                         else:
-                            raise RuntimeError(f"Failed to copy {source_key}: {e}")
+                            raise RuntimeError(f"Failed to copy {source_key}: {e}") from e
 
         self.log.info("Successfully copied %s object(s)", copied_object_count)
 

providers/amazon/tests/unit/amazon/aws/operators/test_s3.py

@@ -860,10 +860,13 @@ def mock_copy_object(*args, **kwargs):
                 raise Exception("Copy failed for file1")
             return None
 
-        with mock.patch.object(op.hook, "copy_object", side_effect=mock_copy_object):
+        with mock.patch.object(op.hook, "copy_object", side_effect=mock_copy_object) as mock_copy:
             with pytest.raises(RuntimeError, match=r"Failed to copy 1 object\(s\)"):
                 op.execute(None)
 
+        attempted_keys = [call.kwargs["source_bucket_key"] for call in mock_copy.call_args_list]
+        assert f"{self.source_prefix}file2.txt" in attempted_keys
+
     @pytest.mark.parametrize(
         "op_kwargs",
         [