Multi-ancestor detector added.

awx/api/views.py

@@ -71,7 +71,6 @@ from awx.api.metadata import RoleMetadata
 from awx.main.consumers import emit_channel_notification
 from awx.main.scheduler.dag_simple import SimpleDAG
 
-
 logger = logging.getLogger('awx.api.views')
 
 def api_exception_handler(exc, context):
@@ -2677,7 +2676,10 @@ class WorkflowJobTemplateNodeChildrenBaseList(EnforceParentRelationshipMixin, Su
             graph.add_edge(parent, sub, self.relationship)
 
         if graph.cycle_detected():
-            return {"Error": "cycle detected!"}
+            return {"Error": "Cycle detected!"}
+
+        if graph.multi_ancestor_detected():
+            return {"Error": "Multiple ancestor detected!"}
 
         return None
 

awx/main/scheduler/dag_simple.py

@@ -174,3 +174,16 @@ class SimpleDAG(object):
 
         self._clean_meta()
         return False
+
+    def multi_ancestor_detected(self):
+        for node in self.nodes:
+            node['metadata'] = {"ancestor": None}
+        for edge in self.edges:
+            if self.nodes[edge[1]]['metadata']['ancestor'] is None:
+                self.nodes[edge[1]]['metadata']['ancestor'] = self.nodes[edge[0]]
+            else:
+                self._clean_meta()
+                return True
+
+        self._clean_meta()
+        return False