Rollback rescue function not working as expected JunOS 19.4R3.11

[dseira]

I'm playing with pyez to restore configuration from rescue but it is not working as expected with the JunOS 19.4R3.11 (also tried with JunOS 20.3R1).

The scenario is:

router1.lab -> JunOS 19.4R3.11
router2.lab -> JunOS 18.2R3-S5.3

The code I am using is very simple:

with Device(host='router1.lab', user=username, password=password) as dev:
    with Config(dev, mode='exclusive') as cu:
        cu.load('set interfaces ae1 unit 11000 vlan-id 4000', format='set')
        cu.pdiff()
        cu.commit()

The pdiff just shows the following:

[edit interfaces ae1]
+    unit 11000 {
+        vlan-id 4000;
+    }

To rollback to the rescue, the code is:

with Device(host=router,user=username, password=password) as dev:
    with Config(dev, mode='exclusive') as cu:
        rescue = cu.rescue(action="reload")
        if rescue is False:
            print ("No existing rescue configuration.")
        else:
            cu.pdiff()
            cu.commit()

In both cases (router1 and router2) the pdiff show:

[edit interfaces ae1]
-    unit 11000 {
-        vlan-id 4000;
-    }

The strange behaviour is that in router1 (19.4R3.11) some "ghost" configuration is left:

show configuration interfaces ae1 unit 11000

Shows nothing as expected in both routers. But in router1 the command:

show interfaces ae1.11000

Shows unit interface related info (just in router1):

  Logical interface ae1.11000 (Index 101) (SNMP ifIndex 591)
    Flags: Up SNMP-Traps 0x4000 VLAN-Tag [ 0x8100.4000 ]  Encapsulation: ENET2
    Statistics        Packets        pps         Bytes          bps
    Bundle:
        Input :             0          0             0            0
        Output:             0          0             0            0

Furthermore, should you call cu.rollback(1) instead of cu.rescue, the pdiff shows the same as with rescue:

[edit interfaces ae1]
-    unit 11000 {
-        vlan-id 4000;
-    }

But in this case, the "ghost" configuration isn't left (as expected):

router1> show interfaces ae1.11000
error: interface ae1.11000 not found

Is there something that I'm missing on using the cu.rescue?