Fix problem with context data on password reset email (#2455)

Allauth sent context that wasn't able to serialize with pickle when passing to
Celery. Remove the data, as it wasn't even needed anyways.

Fixes #2442

Author: agjohnson

readthedocs/core/adapters.py

@@ -1,5 +1,8 @@
 """Allauth overrides"""
 
+import pickle
+import logging
+
 from allauth.account.adapter import DefaultAccountAdapter
 from django.template.loader import render_to_string
 
@@ -10,6 +13,8 @@
 except ImportError:
     from django.utils.encoding import force_unicode as force_text
 
+log = logging.getLogger(__name__)
+
 
 class AccountAdapter(DefaultAccountAdapter):
 
@@ -25,6 +30,19 @@ def send_mail(self, template_prefix, email, context):
         subject = " ".join(subject.splitlines()).strip()
         subject = self.format_email_subject(subject)
 
+        # Allauth sends some additional data in the context, remove it if the
+        # pieces can't be pickled
+        removed_keys = []
+        for key in context.keys():
+            try:
+                _ = pickle.dumps(context[key])
+            except pickle.PickleError:
+                removed_keys.append(key)
+                del context[key]
+        if removed_keys:
+            log.debug('Removed context we were unable to serialize: %s',
+                      removed_keys)
+
         send_email(
             recipient=email,
             subject=subject,