Correct ASSERT_OK() in ReadDroppedColumnFamily

Summary: ReadDroppedColumnFamily is consistently failing in Travis CI environment (can't repro locally). I suspect it might be failing with non-OK status. This diff will give us more info about the failure.

Test Plan: none

Reviewers: sdong, kradhakrishnan

Reviewed By: kradhakrishnan

Subscribers: kradhakrishnan, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46611

db/column_family_test.cc

@@ -1187,6 +1187,7 @@ TEST_F(ColumnFamilyTest, ReadDroppedColumnFamily) {
         ASSERT_OK(iterator->status());
         ++count;
       }
+      ASSERT_OK(iterator->status());
       ASSERT_EQ(count, kKeysNum * ((i == 2) ? 1 : 2));
     }