fix bug from rev 652 - triggered when n in {(nmini*kmini):(nmini*(kmini+1)-1)} i.e. by default n in 1501:1799

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/robustbase@656 694ef91d-65df-0310-b7bb-92e67a308ead