Fix problem with context data on password reset email

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,