Fixed #16245 -- Included traceback in send_robust()'s response

Exceptions from the (receiver, exception) tuples returned by
``send_robust()`` now have always their traceback attached as their
``__traceback__`` argument.

1 files changed, 4 insertions, 1 deletions

diff --git a/django/dispatch/dispatcher.py b/django/dispatch/dispatcher.py
index ba97077ce5..20048f5c55 100644
--- a/django/dispatch/dispatcher.py
+++ b/django/dispatch/dispatcher.py
@@ -220,7 +220,8 @@ class Signal(object):
 
         If any receiver raises an error (specifically any subclass of
         Exception), the error instance is returned as the result for that
-        receiver.
+        receiver. The traceback is always attached to the error at
+        ``__traceback__``.
         """
         responses = []
         if not self.receivers or self.sender_receivers_cache.get(sender) is NO_RECEIVERS:
@@ -232,6 +233,8 @@ class Signal(object):
             try:
                 response = receiver(signal=self, sender=sender, **named)
             except Exception as err:
+                if not hasattr(err, '__traceback__'):
+                    err.__traceback__ = sys.exc_info()[2]
                 responses.append((receiver, err))
             else:
                 responses.append((receiver, response))