make fact saving code more robust to unexpected fact data

see: https://github.com/ansible/awx/issues/5935

awx/main/models/jobs.py

@@ -829,8 +829,10 @@ class Job(UnifiedJob, JobOptions, SurveyJobMixin, JobNotificationMixin, TaskMana
                             continue
                         host.ansible_facts = ansible_facts
                         host.ansible_facts_modified = now()
-                        ansible_local_system_id = ansible_facts.get('ansible_local', {}).get('insights', {}).get('system_id', None)
+                        ansible_local = ansible_facts.get('ansible_local', {}).get('insights', {})
-                        ansible_facts_system_id = ansible_facts.get('insights', {}).get('system_id', None)
+                        ansible_facts = ansible_facts.get('insights', {})
+                        ansible_local_system_id = ansible_local.get('system_id', None) if isinstance(ansible_local, dict) else None
+                        ansible_facts_system_id = ansible_facts.get('system_id', None) if isinstance(ansible_facts, dict) else None
                         if ansible_local_system_id:
                             print("Setting local {}".format(ansible_local_system_id))
                             logger.debug("Insights system_id {} found for host <{}, {}> in"

awx/main/tests/unit/models/test_jobs.py

@@ -89,6 +89,27 @@ def test_finish_job_fact_cache_with_existing_data(job, hosts, inventory, mocker,
     hosts[1].save.assert_called_once_with()
 
 
+def test_finish_job_fact_cache_with_malformed_fact(job, hosts, inventory, mocker, tmpdir):
+    fact_cache = os.path.join(tmpdir, 'facts')
+    modified_times = {}
+    job.start_job_fact_cache(fact_cache, modified_times, 0)
+
+    for h in hosts:
+        h.save = mocker.Mock()
+
+    for h in hosts:
+        filepath = os.path.join(fact_cache, h.name)
+        with open(filepath, 'w') as f:
+            json.dump({'ansible_local': {'insights': 'this is an unexpected error from ansible'}}, f)
+            new_modification_time = time.time() + 3600
+            os.utime(filepath, (new_modification_time, new_modification_time))
+
+    job.finish_job_fact_cache(fact_cache, modified_times)
+
+    for h in hosts:
+        assert h.insights_system_id is None
+
+
 def test_finish_job_fact_cache_with_bad_data(job, hosts, inventory, mocker, tmpdir):
     fact_cache = os.path.join(tmpdir, 'facts')
     modified_times = {}