Merge pull request #6290 from ansible/fix_sysjobs_taskman_credentials

Fix system jobs not starting due to task manager and cred changes

awx/main/models/jobs.py

@@ -1344,6 +1344,10 @@ class SystemJob(UnifiedJob, SystemJobOptions, JobNotificationMixin):
     def task_impact(self):
         return 150
 
+    @property
+    def preferred_instance_groups(self):
+        return self.global_instance_groups
+
     '''
     JobNotificationMixin
     '''

awx/main/tasks.py

@@ -737,8 +737,10 @@ class BaseTask(Task):
             # handle custom injectors specified on the CredentialType
             if hasattr(instance, 'all_credentials'):
                 credentials = instance.all_credentials
-            else:
+            elif hasattr(instance, 'credential'):
                 credentials = [instance.credential]
+            else:
+                credentials = []
             for credential in credentials:
                 if credential:
                     credential.credential_type.inject_credential(