Fix #249 -- Blacklist some exceptions for celeries error reporting

src/pretix/celery.py

@@ -1,6 +1,7 @@
 import os
 
 from celery import Celery
+from celery.utils.mail import ErrorMail
 
 os.environ.setdefault("DJANGO_SETTINGS_MODULE", "pretix.settings")
 
@@ -8,5 +9,21 @@ from django.conf import settings
 
 app = Celery('pretix')
 
+
+class MyErrorMail(ErrorMail):
+
+    def should_send(self, context, exc):
+        from pretix.base.services.orders import OrderError
+        from pretix.base.services.cart import CartError
+
+        blacklist = (OrderError, CartError)
+        return not isinstance(exc, blacklist)
+
+
 app.config_from_object('django.conf:settings')
+app.conf.CELERY_ANNOTATIONS = {
+    '*': {
+        'ErrorMail': MyErrorMail,
+    }
+}
 app.autodiscover_tasks(lambda: settings.INSTALLED_APPS)