closes #1758 also for R 2.15
closes #1758 also for R 2.15

vlulla/data.table,Rdatatable/data.table,jangorecki/data.table,Rdatatable/data.table,jangorecki/data.table,Rdatatable/data.table,vlulla/data.table,Rdatatable/data.table,jangorecki/data.table,jangorecki/data.table,vlulla/data.table,vlulla/data.table