Merge pull request scrapy#805 from darkrho/spiderstate-jobdir

For consistency, use `job_dir` helper in `SpiderState` extension.

scrapy/contrib/spiderstate.py

@@ -2,6 +2,7 @@
 from six.moves import cPickle as pickle
 
 from scrapy import signals
+from scrapy.utils.job import job_dir
 
 class SpiderState(object):
     """Store and load spider state during a scraping job"""
@@ -11,7 +12,7 @@ def __init__(self, jobdir=None):
 
     @classmethod
     def from_crawler(cls, crawler):
-        obj = cls(crawler.settings.get('JOBDIR'))
+        obj = cls(job_dir(crawler.settings))
         crawler.signals.connect(obj.spider_closed, signal=signals.spider_closed)
         crawler.signals.connect(obj.spider_opened, signal=signals.spider_opened)
         return obj