can't pull from embedded document field

[dblado]

django-mongoengine==0.3.3
mongoengine==0.17.0

I have the following models in a Django app:

from django_mongoengine import Document, EmbeddedDocument, fields

class TestEmbModel(EmbeddedDocument):
    list_of_strings = fields.ListField(fields.StringField(), blank=True)

class TestModel(Document):
    some_embedded_doc = fields.EmbeddedDocumentField('TestEmbModel', blank=True)

When using:

a=TestModel()
a.save()

This works:
a.update(add_to_set__some_embedded_doc__list_of_strings='abc')

This does not work:
a.update(pull__some_embedded_doc__list_of_strings='abc')

---------------------------------------------------------------------------
OperationError                            Traceback (most recent call last)
<ipython-input-1-3e6ce99e224a> in <module>()
     14 
     15 a.update(add_to_set__some_embedded_doc__list_of_strings='abc')
---> 16 a.update(pull__some_embedded_doc__list_of_strings='abc')

/Users/dblado/.virtualenvs/vendop/lib/python2.7/site-packages/mongoengine/document.pyc in update(self, **kwargs)
    593 
    594         # Need to add shard key to query, or you get an error
--> 595         return self._qs.filter(**self._object_key).update_one(**kwargs)
    596 
    597     def delete(self, signal_kwargs=None, **write_concern):

/Users/dblado/.virtualenvs/vendop/lib/python2.7/site-packages/mongoengine/queryset/base.pyc in update_one(self, upsert, write_concern, full_result, **update)
    592             write_concern=write_concern,
    593             full_result=full_result,
--> 594             **update)
    595 
    596     def modify(self, upsert=False, full_response=False, remove=False, new=False, **update):

/Users/dblado/.virtualenvs/vendop/lib/python2.7/site-packages/mongoengine/queryset/base.pyc in update(self, upsert, multi, write_concern, full_result, **update)
    541                 message = u'update() method requires MongoDB 1.1.3+'
    542                 raise OperationError(message)
--> 543             raise OperationError(u'Update failed (%s)' % six.text_type(err))
    544 
    545     def upsert_one(self, write_concern=None, **update):

OperationError: Update failed (Cannot apply $pull to a non-array value)

If I change Document, EmbeddedDocument to use mongoengine instead of django_mongoengine it works:

from mongoengine import Document, EmbeddedDocument, fields

I think this is related to MongoEngine/mongoengine#1534