we don't try to access a nonexistent stored level exit.
git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@6362 c06c8d41-db1a-0410-9941-cceddc491573
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25EX6COTFUVEIGQMCJ47FDSEKASVVO74LPJ4ZS66ZYUYXD5G3N3QC
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EMOBSWJHHB4V6WVMZL7JCF2V3KZN454Z6NS346OKFPMBNO24EJDQC
static int e_index;
static int e_index = -1;