test iterator after wal_threshold
test iterator after wal_threshold

create 1 kvs with 600 docs
then copy into 2nd kvs, which passes wal_threshold of 1024
attempt to iterate over docs in first kvs

Change-Id: I06c461a897cd9a295f770bd3efa23bc9389ad455

couchbase/forestdb,hisundar/forestdb,yyangpan/forestdb,hisundar/forestdb,sushmaad/forestdb,yyangpan/forestdb,couchbase/forestdb,seem-sky/forestdb,zhaog/forestdb,wurikiji/forestdb,nvoron23/forestdb,jinxuan/forestdb,zhaog/forestdb,nvoron23/forestdb,joliss/forestdb,sushmaad/forestdb,joliss/forestdb,wurikiji/forestdb,seem-sky/forestdb,jinxuan/forestdb