Minor changes to shallow() for internal use.
Minor changes to shallow() for internal use.

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