Fix inverted logic (oops).

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@7155 c06c8d41-db1a-0410-9941-cceddc491573

Created by  dolorous  on October 6, 2008
4XNGREELPJNZTIRS6QX5YNUW6TBDHOCKTJLGQ4MSWJHI4EBLTAQQC
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