update reverse level when co is replaced

src/base/abc/abcAig.c

@@ -897,6 +897,16 @@ void Abc_AigReplace_int( Abc_Aig_t * pMan, Abc_Obj_t * pOld, Abc_Obj_t * pNew, i
     {
         if ( Abc_ObjIsCo(pFanout) )
         {
+            pFanin1 = Abc_ObjRegular( pNew );
+            if ( pFanin1->fMarkB )
+                Abc_AigRemoveFromLevelStructureR( pMan->vLevelsR, pFanin1 );
+            if ( fUpdateLevel && pMan->pNtkAig->vLevelsR )
+            {
+                Abc_ObjSetReverseLevel( pFanin1, Abc_ObjReverseLevel(pOld) );
+                assert( pFanin1->fMarkB == 0 );
+                pFanin1->fMarkB = 1;
+                Vec_VecPush( pMan->vLevelsR, Abc_ObjReverseLevel(pFanin1), pFanin1 );
+            }
             Abc_ObjPatchFanin( pFanout, pOld, pNew );
             continue;
         }