Addressing review comments.

Author: dhermes

gcloud/bigtable/row.py

@@ -410,10 +410,10 @@ def _commit_check_and_mutate(self):
     def clear_mutations(self):
         """Removes all currently accumulated mutations on the current row."""
         if self._filter is None:
-            self._pb_mutations[:] = []
+            del self._pb_mutations[:]
         else:
-            self._true_pb_mutations[:] = []
-            self._false_pb_mutations[:] = []
+            del self._true_pb_mutations[:]
+            del self._false_pb_mutations[:]
 
     def commit(self):
         """Makes a ``MutateRow`` or ``CheckAndMutateRow`` API request.

gcloud/bigtable/test_row.py

@@ -460,21 +460,30 @@ def test_commit_with_filter(self):
         row = self._makeOne(row_key, table, filter_=row_filter)
 
         # Create request_pb
-        value = b'bytes-value'
-        mutation = data_pb2.Mutation(
+        value1 = b'bytes-value'
+        mutation1 = data_pb2.Mutation(
             set_cell=data_pb2.Mutation.SetCell(
                 family_name=column_family_id,
                 column_qualifier=column,
                 timestamp_micros=-1,  # Default value.
-                value=value,
+                value=value1,
+            ),
+        )
+        value2 = b'other-bytes'
+        mutation2 = data_pb2.Mutation(
+            set_cell=data_pb2.Mutation.SetCell(
+                family_name=column_family_id,
+                column_qualifier=column,
+                timestamp_micros=-1,  # Default value.
+                value=value2,
             ),
         )
         request_pb = messages_pb2.CheckAndMutateRowRequest(
             table_name=table_name,
             row_key=row_key,
             predicate_filter=row_filter.to_pb(),
-            true_mutations=[mutation],
-            false_mutations=[],
+            true_mutations=[mutation1],
+            false_mutations=[mutation2],
         )
 
         # Create response_pb
@@ -489,7 +498,8 @@ def test_commit_with_filter(self):
         expected_result = predicate_matched
 
         # Perform the method and check the result.
-        row.set_cell(column_family_id, column, value, state=True)
+        row.set_cell(column_family_id, column, value1, state=True)
+        row.set_cell(column_family_id, column, value2, state=False)
         result = row.commit()
         self.assertEqual(result, expected_result)
         self.assertEqual(stub.method_calls, [(