gistfile1.diff

diff --git a/scrapy/commands/shell.py b/scrapy/commands/shell.py
index 7c07064..d57643a 100644
--- a/scrapy/commands/shell.py
+++ b/scrapy/commands/shell.py
@@ -16,7 +16,8 @@ from scrapy.utils.spider import spidercls_for_request, DefaultSpider
 class Command(ScrapyCommand):
 
     requires_project = False
-    default_settings = {'KEEP_ALIVE': True, 'LOGSTATS_INTERVAL': 0}
+    default_settings = {'KEEP_ALIVE': True, 'LOGSTATS_INTERVAL': 0,
+            'DUPEFILTER_CLASS': 'scrapy.dupefilter.BaseDupeFilter'}
 
     def syntax(self):
         return "[url|file]"