Traceback thrown by mongodb backend for scrapy (https://github.com/noplay/scrapy-mongodb)

gistfile1.py

	Traceback (most recent call last):
	  File "/Users/ciferkey/.virtualenvs/scraper/lib/python2.7/site-packages/scrapy/middleware.py", line 54, in _process_chain
	    return process_chain(self.methods[methodname], obj, *args)
	  File "/Users/ciferkey/.virtualenvs/scraper/lib/python2.7/site-packages/scrapy/utils/defer.py", line 65, in process_chain
	    d.callback(input)
	  File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/twisted/internet/defer.py", line 361, in callback
	    self._startRunCallbacks(result)
	  File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/twisted/internet/defer.py", line 455, in _startRunCallbacks
	    self._runCallbacks()
	--- <exception caught here> ---
	  File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/twisted/internet/defer.py", line 542, in _runCallbacks
	    current.result = callback(current.result, *args, **kw)
	  File "/Users/ciferkey/.virtualenvs/scraper/lib/python2.7/site-packages/scrapymongodb.py", line 34, in process_item
	    {self.__get_uniq_key(): item[self.__get_uniq_key()]},
	  File "/Users/ciferkey/.virtualenvs/scraper/lib/python2.7/site-packages/scrapy/item.py", line 49, in __getitem__
	    return self._values[key]
	exceptions.KeyError: 'url'