Was using wrong method to get the last element of a vector.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@8624 c06c8d41-db1a-0410-9941-cceddc491573

Created by  zelgadis  on January 20, 2009
XDWH6DBJUHQLLGTTL7WMWVAIW5P576HTPESF7XUTP5H7PU5CX5OAC
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