Fix dangling file descriptor in FeedExporter when FEED_STORE_EMPTY is False (#4023)

scrapy/extensions/feedexport.py

@@ -242,7 +242,9 @@ class FeedExporter(object):
     def close_spider(self, spider):
         slot = self.slot
         if not slot.itemcount and not self.store_empty:
-            return
+            # We need to call slot.storage.store nonetheless to get the file
+            # properly closed.
+            return defer.maybeDeferred(slot.storage.store, slot.file)
         if self._exporting:
             slot.exporter.finish_exporting()
             self._exporting = False

tests/test_feedexport.py

@@ -417,7 +417,7 @@ class FeedExportTest(unittest.TestCase):
                 content = f.read()
 
         finally:
-            shutil.rmtree(tmpdir, ignore_errors=True)
+            shutil.rmtree(tmpdir)
 
         defer.returnValue(content)