simpler approach and dont override role collection

lib/ansible/playbook/collectionsearch.py

@@ -47,7 +47,7 @@ class CollectionSearch:
         # this will only be called if someone specified a value; call the shared value
         _ensure_default_collection(collection_list=ds)
 
-        # ensure 'current's object collection is here', only playbooks and plays should have this property
+        # ensure 'current's object collection is here', only playbooks, plays and roles should have this property
         if getattr(self, '_collection', False) and self._collection not in ds:
             ds.insert(0, self._collection)
 

lib/ansible/playbook/role/definition.py

@@ -57,6 +57,9 @@ class RoleDefinition(Base, Conditional, Taggable, CollectionSearch):
         self._role_collection = None
         self._role_basedir = role_basedir
         self._role_params = dict()
+        if collection_list is None:
+            self._collection_list = []
+        else:
             self._collection_list = collection_list
 
     # def __repr__(self):
@@ -154,16 +157,12 @@ class RoleDefinition(Base, Conditional, Taggable, CollectionSearch):
 
         role_tuple = None
 
-        # ensure play collection context
-        if self._play._collection:
-            if not self._collection_list:
-                self._collection_list = [self._play._collection]
-            elif self._play._collection not in self._collection_list:
-                self._collection_list.insert(0, self._play._collection)
-
         # try to load as a collection-based role first
         if self._collection_list or AnsibleCollectionRef.is_valid_fqcr(role_name):
             role_tuple = _get_collection_role_path(role_name, self._collection_list)
+        elif self._play._collection:
+            # ensure play collection context when role does not have one
+            role_tuple = _get_collection_role_path(role_name, [self._play._collection])
 
         if role_tuple:
             # we found it, stash collection data and return the name/path tuple
@@ -206,7 +205,7 @@ class RoleDefinition(Base, Conditional, Taggable, CollectionSearch):
             role_name = os.path.basename(role_name)
             return (role_name, role_path)
 
-        searches = (self._collection_list or []) + role_search_paths
+        searches = (self._collection_list) + role_search_paths
         raise AnsibleError("the role '%s' was not found in %s" % (role_name, ":".join(searches)), obj=self._ds)
 
     def _split_role_params(self, ds):