now passes the test of skipping list when dict attribute is undefined, added…

now passes the test of skipping list when dict attribute is undefined, added deprecation warning as this seems like bad behaviour

lib/ansible/executor/task_executor.py

@@ -26,7 +26,7 @@ import sys
 import time
 
 from ansible import constants as C
-from ansible.errors import AnsibleError, AnsibleParserError
+from ansible.errors import AnsibleError, AnsibleParserError, AnsibleUndefinedVariable
 from ansible.playbook.conditional import Conditional
 from ansible.playbook.task import Task
 from ansible.plugins import connection_loader, action_loader
@@ -154,7 +154,14 @@ class TaskExecutor:
         if self._task.loop:
             if self._task.loop in self._shared_loader_obj.lookup_loader:
                 #TODO: remove convert_bare true and deprecate this in with_ 
-                loop_terms = listify_lookup_plugin_terms(terms=self._task.loop_args, templar=templar, loader=self._loader, fail_on_undefined=True, convert_bare=True)
+                try:
+                    loop_terms = listify_lookup_plugin_terms(terms=self._task.loop_args, templar=templar, loader=self._loader, fail_on_undefined=True, convert_bare=True)
+                except AnsibleUndefinedVariable as e:
+                    if 'has no attribute' in str(e):
+                        loop_terms = []
+                        self._display.deprecated("Skipping task due to undefined attribute, in the future this will be a fatal error.")
+                    else:
+                        raise
                 items = self._shared_loader_obj.lookup_loader.get(self._task.loop, loader=self._loader, templar=templar).run(terms=loop_terms, variables=vars_copy)
             else:
                 raise AnsibleError("Unexpected failure in finding the lookup named '%s' in the available lookup plugins" % self._task.loop)

lib/ansible/template/__init__.py

@@ -256,8 +256,8 @@ class Templar:
             # safely catch run failures per #5059
             try:
                 ran = instance.run(loop_terms, variables=self._available_variables, **kwargs)
-            except (AnsibleUndefinedVariable, UndefinedError):
-                raise
+            except (AnsibleUndefinedVariable, UndefinedError) as e:
+                raise AnsibleUndefinedVariable(e)
             except Exception, e:
                 if self._fail_on_lookup_errors:
                     raise
@@ -337,7 +337,7 @@ class Templar:
             return res
         except (UndefinedError, AnsibleUndefinedVariable), e:
             if fail_on_undefined:
-                raise
+                raise AnsibleUndefinedVariable(e)
             else:
                 #TODO: return warning about undefined var
                 return data