Don't dynamically create provider types in the global env

Only support this in user environments.
Note: this is only when you have the following in your template
resources:
  thingy:
    type: http://example.com/foo.template

Doing this will avoid tenant-specific provider template URLs being
shown globally in the resource-type listing.

Co-Authored-By: Angus Salkeld <angus.salkeld@rackspace.com>
Closes-Bug: #1311223
Change-Id: Ifa18108afacbda390b19b46a8f41bc4f018e95d6

heat/engine/environment.py

@@ -217,7 +217,10 @@ class ResourceRegistry(object):
         registry[name] = info
 
     def iterable_by(self, resource_type, resource_name=None):
-        if resource_type.endswith(('.yaml', '.template')):
+        is_templ_type = resource_type.endswith(('.yaml', '.template'))
+        if self.global_registry is not None and is_templ_type:
+            # we only support dynamic resource types in user environments
+            # not the global environment.
             # resource with a Type == a template
             # we dynamically create an entry as it has not been registered.
             if resource_type not in self._registry:

heat/tests/test_provider_template.py

@@ -428,6 +428,8 @@ class ProviderTemplateTest(HeatTestCase):
             {'WordPress_Single_Instance.yaml':
              'WordPress_Single_Instance.yaml', 'resources': {}},
             stack.env.user_env_as_dict()["resource_registry"])
+        self.assertNotIn('WordPress_Single_Instance.yaml',
+                         resources.global_env().registry._registry)
 
     def test_persisted_unregistered_provider_templates(self):
         """