fixup! Eagerly check for circular dependencies

buildstream/_loader/loadelement.py

@@ -136,7 +136,7 @@ class LoadElement():
     # Raises:
     #   (LoadError): In case there was a circular dependency
     #
-    def _ensure_no_circular_deps(self):
+    def ensure_no_circular_deps(self):
         if self._node_id in self._dep_cache:
             self._find_circular_deps(set(), set(), [])
 

buildstream/_loader/loader.py

@@ -261,7 +261,7 @@ class Loader():
         deps_names = [dep.name for dep in dependencies]
         self._warn_invalid_elements(deps_names)
 
-        element._ensure_no_circular_deps()
+        element.ensure_no_circular_deps()
 
         return element