Rebuild flat_graph after deferral

core/dbt/contracts/graph/manifest.py

@@ -1018,6 +1018,10 @@ class Manifest(MacroMethods, DataClassMessagePackMixin, dbtClassMixin):
                 merged.add(unique_id)
                 self.nodes[unique_id] = node.replace(deferred=True)
 
+        # (Option A)
+        # Rebuild the flat_graph, which powers the 'graph' context variable,
+        # now that we've deferred some nodes
+        self.build_flat_graph()
         # log up to 5 items
         sample = list(islice(merged, 5))
         fire_event(MergedFromState(nbr_merged=len(merged), sample=sample))

core/dbt/task/run.py

@@ -433,6 +433,10 @@ class RunTask(CompileTask):
             other=deferred_manifest,
             selected=selected_uids,
         )
+        # (Option B)
+        # Rebuild the flat_graph, which powers the 'graph' context variable,
+        # now that we've deferred some nodes
+        self.manifest.build_flat_graph()
         # TODO: is it wrong to write the manifest here? I think it's right...
         self.write_manifest()