[Backport] Throw a signal when users change their email adress

taiga/users/api.py

@@ -47,6 +47,7 @@ from . import permissions
 from . import filters as user_filters
 from . import services
 from .signals import user_cancel_account as user_cancel_account_signal
+from .signals import user_change_email as user_change_email_signal
 
 
 class UsersViewSet(ModelCrudViewSet):
@@ -273,11 +274,20 @@ class UsersViewSet(ModelCrudViewSet):
                                        "didn't use it before?"))
 
         self.check_permissions(request, "change_email", user)
-        user.email = user.new_email
+
+        old_email = user.email
+        new_email = user.new_email
+
+        user.email = new_email
         user.new_email = None
         user.email_token = None
         user.save(update_fields=["email", "new_email", "email_token"])
 
+        user_change_email_signal.send(sender=user.__class__,
+                                      user=user,
+                                      old_email=old_email,
+                                      new_email=new_email)
+
         return response.NoContent()
 
     @list_route(methods=["GET"])

taiga/users/signals.py

@@ -19,4 +19,5 @@
 import django.dispatch
 
 
+user_change_email = django.dispatch.Signal(providing_args=["user", "old_email", "new_email"])
 user_cancel_account = django.dispatch.Signal(providing_args=["user", "request_data"])