fixes bug report #5876

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/xts@832 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
fixes bug #5874

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/xts@833 edb9625f-4e0d-4859-8d74-9fd3b1da38cb