Update R/as.data.table.R

Author: ben-schwen

R/as.data.table.R

@@ -245,8 +245,8 @@ as.data.table.data.frame = function(x, keep.rownames=FALSE, key=NULL, ...) {
   ans
 }
 
-as.data.table.data.table = function(x, keep.rownames, key, ...) {
-  if (missing(key))  key = NULL
+as.data.table.data.table = function(x, keep.rownames, key=NULL, ...) {
+
   # as.data.table always returns a copy, automatically takes care of #473
   if (any(cols_with_dims(x))) { # for test 2089.2
     return(as.data.table.list(x, key = key, ...))