Keep Trace Back in Exception

While catching exception, we should use 'raise' directly if we parsing
same exception to upper level. In this way, we will not losing trace
back information.

Change-Id: I9cb208bb355082907b789dffa8de28dd33c9f01d

heat/engine/clients/os/barbican.py

@@ -62,7 +62,7 @@ class BarbicanClientPlugin(client_plugin.ClientPlugin):
                 raise exception.EntityNotFound(
                     entity="Secret",
                     name=secret_ref)
-            raise ex
+            raise
 
     def get_container_by_ref(self, container_ref):
         try:
@@ -73,7 +73,7 @@ class BarbicanClientPlugin(client_plugin.ClientPlugin):
                 raise exception.EntityNotFound(
                     entity="Container",
                     name=container_ref)
-            raise ex
+            raise
 
 
 class SecretConstraint(constraints.BaseCustomConstraint):

heat/engine/clients/os/mistral.py

@@ -59,7 +59,7 @@ class MistralClientPlugin(client_plugin.ClientPlugin):
                 raise exception.EntityNotFound(
                     entity="Workflow",
                     name=workflow_identifier)
-            raise ex
+            raise
 
 
 class WorkflowConstraint(constraints.BaseCustomConstraint):

heat/engine/resource.py

@@ -1734,7 +1734,7 @@ class Resource(object):
             if self.client_plugin().is_not_found(ex):
                 raise exception.EntityNotFound(
                     entity='Resource', name=self.name)
-            raise ex
+            raise
         return resource_data
 
     def parse_live_resource_data(self, resource_properties, resource_data):

heat/engine/resources/openstack/senlin/policy.py

@@ -107,7 +107,7 @@ class Policy(resource.Resource):
                         self.client_plugin().is_not_found(ex)):
                     bd['finished'] = True
                 else:
-                    raise ex
+                    raise
 
     def add_bindings(self, bindings):
         for bd in bindings:

heat/engine/resources/openstack/trove/os_database.py

@@ -500,7 +500,7 @@ class OSDBInstance(resource.Resource):
                         LOG.warning(_LW("Unexpected instance state change "
                                         "during update. Retrying."))
                         return False
-                raise exc
+                raise
         return True
 
     def _update_name(self, instance, name):

heat/engine/stack.py

@@ -762,7 +762,7 @@ class Stack(collections.Mapping):
                 if ignorable_errors and ex.error_code in ignorable_errors:
                     result = None
                 else:
-                    raise ex
+                    raise
             except AssertionError:
                 raise
             except Exception as ex: