Disconnect signals since they have already been called.

see #1489

modoboa/relaydomains/forms.py

@@ -4,12 +4,37 @@
 
 from __future__ import unicode_literals
 
+from django.db.models.signals import pre_save, post_save
+
 from modoboa.lib.form_utils import WizardStep
 from modoboa.transport import forms as tr_forms, models as tr_models
 
 
-class RelayDomainWizardStep(WizardStep):
+class DisableSignals(object):
+    """Context manager to disable signals."""
 
+    def __init__(self):
+        self.stashed_signals = {}
+        self.disabled_signals = [pre_save, post_save]
+
+    def __enter__(self):
+        for signal in self.disabled_signals:
+            self.disconnect(signal)
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        for signal in self.stashed_signals.keys():
+            self.reconnect(signal)
+
+    def disconnect(self, signal):
+        self.stashed_signals[signal] = signal.receivers
+        signal.receivers = []
+
+    def reconnect(self, signal):
+        signal.receivers = self.stashed_signals.get(signal, [])
+        del self.stashed_signals[signal]
+
+
+class RelayDomainWizardStep(WizardStep):
     """A custom wizard step."""
 
     def check_access(self, wizard):
@@ -39,5 +64,6 @@ class RelayDomainFormGeneral(tr_forms.TransportForm):
         instance.save()
         if not domain.transport:
             domain.transport = instance
-            domain.save(update_fields=["transport"])
+            with DisableSignals():
+                domain.save(update_fields=["transport"])
         return instance