Make .xts() not return an object with row names

.xts() would return an object with row names when passed a matrix with
row names. But xts objects never have a 'rownames' attribute.

Fixes #298.

R/xts.R

@@ -191,6 +191,11 @@ function(x=NULL, index, tclass=c("POSIXct","POSIXt"),
   xx <- .Call("add_xtsCoreAttributes", x, index, tzone, tclass,
               c('xts','zoo'), tformat, PACKAGE='xts')
 
+  # ensure there are no rownames
+  if(!is.null((dimnames(xx)))) {
+    dimnames(xx)[[1]] <- NULL
+  }
+
   # remove any index attributes that came through '...'
   # and set any user attributes (and/or dim, dimnames, etc)
   dots.names <- eval(substitute(alist(...)))

inst/unitTests/runit.xts.R

@@ -113,6 +113,12 @@ test..xts_dimnames_in_dots <- function() {
   checkEquals(x, y)
 }
 
+test..xts_ctor_does_not_return_rownames <- function() {
+  m <- matrix(1, dimnames = list("a", "b"))
+  x <- .xts(m, 1)
+  checkEquals(rownames(x), NULL)
+}
+
 test..xts_ctor_warns_if_index_tclass_not_NULL_or_POSIXct <- function() {
   DEACTIVATED("Warning causes errors in dependencies")
   op <- options(warn = 2)