[fix] Guard missing skip_push_update_on_save in register view #1331

DeviceRegisterView._update_device_name calls
``device.skip_push_update_on_save()`` whenever an agent re-registers
with a hostname different from the MAC address. That method is
referenced in the view but is not implemented on the Device model,
so every such re-registration crashes with HTTP 500:

    AttributeError: 'Device' object has no attribute 'skip_push_update_on_save'

This breaks the consistent_registration / factory-reset workflow:

1. A router does a factory reset → loses its local UUID/key
2. The agent computes ``consistent_key = md5(MAC + "+" + secret)``
   and POSTs ``/controller/register/``.
3. OpenWISP looks up the existing device by the consistent key and
   finds it.
4. The view enters the ``_update_device_name`` branch (because the
   hostname ``<MAC>-fwr-unprovisioned`` differs from the bare MAC).
5. The bogus method call raises ``AttributeError`` and the server
   returns HTTP 500.
6. The agent sees a response without the X-Openwisp-Controller header
   (the 500 error page does not set it) and aborts.
7. After 6 crash retries procd kills the agent.

The router never recovers from a factory reset until an admin
manually deletes the existing device record. This affects every
deployment that uses consistent_registration and runs agents with
hostnames that do not equal the bare MAC (e.g. anything that names
devices by location or status).

Wrap the call in ``getattr`` so the registration path succeeds whether
the helper method exists or not. The actual helper can be reintroduced
later without changing this site; the guard is forward-compatible.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Codex

openwisp_controller/config/controller/views.py

@@ -550,7 +550,15 @@ def _update_device_name(self, request, device):
         normalized_name = name.replace(":", "").replace("-", "").lower()
         if normalized_name != normalized_mac:
             device.name = name
-            device.skip_push_update_on_save()
+            # NOTE: upstream openwisp-controller 1.2 calls
+            # ``device.skip_push_update_on_save()`` here, but that method
+            # was never implemented on the Device model, causing every
+            # re-registration with a non-MAC hostname to crash with
+            # AttributeError. We guard the call so missing methods don't
+            # break factory-reset re-registration.
+            skip = getattr(device, "skip_push_update_on_save", None)
+            if callable(skip):
+                skip()
 
 
 class GetVpnView(SingleObjectMixin, View):