Weird attempt to fix test error

Getting:

eleveldb:async_iterator_close failed
Reason: badarg

When running tests, works on another machine, also fails on travis

stack:

=== Ended at 2014-12-10 18:51:16
=== location [{eleveldb,async_iterator_close},
 {eleveldb,iterator_close,215},
 {eleveldb,do_fold,347},
 {leveltsdb,fold_metric,34},
 {leveltsdb_SUITE,fold_metric,59},
 {test_server,ts_tc,1358},
 {test_server,run_test_case_eval1,975},
 {test_server,run_test_case_eval,924}]
=== reason = bad argument
  in function  eleveldb:async_iterator_close/2
     called as eleveldb:async_iterator_close(#Ref<0.0.0.1557>,<<>>)
  in call from eleveldb:iterator_close/1 (src/eleveldb.erl, line 215)
  in call from eleveldb:do_fold/4 (src/eleveldb.erl, line 347)
  in call from leveltsdb:fold_metric/4 (src/leveltsdb.erl, line 34)
  in call from leveltsdb_SUITE:fold_metric/1 (test/leveltsdb_SUITE.erl, line 59)
  in call from test_server:ts_tc/3 (test_server.erl, line 1358)
  in call from test_server:run_test_case_eval1/6 (test_server.erl, line 975)
  in call from test_server:run_test_case_eval/9 (test_server.erl, line 924)