AsyncSQLToOption.future ignores isSingle flag

[sbmpost]

1. Create a table with 2 rows in it.
2. Execute: withSQL { sqls("select * from table") }.first.future()

This returns TooManyRowsError. The reason is that future() does not take into account the isSingle = false value set by first. See AsyncSQLs.AsyncSQLToOption.

Fix: The implementation of future() should check the isSingle field before calling session.single.

Workaround: Execute with limit like so: withSQL { sqls("select * from table limit 1") }.first.future()