Fix more unit tests in py34 job

- fix: 'dict_values' object does not support indexing
- fix: 'ValueError' object has no attribute 'message'
- fix: RuntimeError: dictionary changed size during iteration

Change-Id: I3581783b84a6785c8d5ad07cbd2d5cb190c73d85

mistral/engine/task_handler.py

@@ -466,7 +466,7 @@ def _schedule_run_workflow(task_ex, task_spec, wf_input, index):
     if 'env' in parent_wf_ex.params:
         wf_params['env'] = parent_wf_ex.params['env']
 
-    for k, v in wf_input.items():
+    for k, v in list(wf_input.items()):
         if k not in wf_spec.get_input():
             wf_params[k] = v
             del wf_input[k]

mistral/expressions.py

@@ -78,7 +78,7 @@ class YAQLEvaluator(Evaluator):
         try:
             YAQL_ENGINE(expression)
         except (yaql_exc.YaqlException, KeyError, ValueError, TypeError) as e:
-            raise exc.YaqlEvaluationException(e.message)
+            raise exc.YaqlEvaluationException(getattr(e, 'message', e))
 
     @classmethod
     def evaluate(cls, expression, data_context):

mistral/workflow/with_items.py

@@ -144,7 +144,7 @@ def prepare_runtime_context(task_ex, task_spec, input_dicts):
 
 def validate_input(with_items_input):
     # Take only mapped values and check them.
-    values = with_items_input.values()
+    values = list(with_items_input.values())
 
     if not all([isinstance(v, list) for v in values]):
         raise exc.InputException(