fix for reloading of strict with special fields

[paularmand]

The following throws an error:

import pymongo as pm
import mongoengine as me
import pprint


db_name = "test_database"
collection_name = "post"
collection_name_items = "post_items"

# get collections through pymongo
client = pm.MongoClient()
db = client[db_name]

# insert a reference document
posts = db[collection_name]
post = {"title": "Lunar eclipse", "body": "lorum ipsim and the rest"}
posts.insert_one(post)

# insert the test document
posts_items = db[collection_name_items]
post_items = {"title": "Items eclipse", "body": "lorum ipsim and the rest", "items": ["more lorem", "even more ipsum"]}
posts_items.insert_one(post_items)


class Post(me.Document):
    meta = {
        'strict': False
    }
    title = me.StringField(required=True, max_length=200)
    body = me.StringField(required=True, max_length=2000)


class PostItems(me.Document):
    meta = {
        'strict': False
    }
    title = me.StringField(required=True, max_length=200)
    body = me.StringField(required=True, max_length=2000)
    items = me.StringField()

me.connect(db_name, alias="default")
post_retrieved = Post.objects().first()
pprint.pprint(post_retrieved)

post_items_retrieved = PostItems.objects().first()
pprint.pprint(post_items_retrieved)
print("should print items")
print post_items_retrieved.items

post_items_retrieved.reload()
print post_items_retrieved.items

the trace:

Traceback (most recent call last):
  File "test.py", line 49, in <module>
    post_items_retrieved.reload()
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/mongoengine/document.py", line 606, in reload
    delattr(self, field)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/mongoengine/base/document.py", line 145, in __delattr__
    super(BaseDocument, self).__delattr__(*args, **kwargs)
AttributeError: _reserved_items

The pull request is resolves the issue by trying to get the field _reserved_items from _data as a fallback.

If you give an indication as to where (in which test class) I need to write the nose test for this issue, I'll do that. On my local platform python setup.py nosetests gives

742 tests run in 32.2 seconds. 
4 skipped (738 tests passed)

[paularmand]

I've added issue #1156 to the changelog and myself to the contributors list as you suggested.

[paularmand]

Thanks, and I've added a test as per your request in the document tests.

[paularmand]

And resolved the merge conflict in AUTHORS.