fix [1997650].
git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@5981 c06c8d41-db1a-0410-9941-cceddc491573
N4RD47CN7EYONUCGUADQEPMRYYOYFXB4YTML5M26HM4RCYUWWRUAC
EYMNSHCYA5455YMSGDF4MCOJKYRTFHXMEPFYYXBR6CPXHOMAQB3AC
QDYSUC5PAW44LDO2AAA4QNZNB6RW5EWRAXBSYATFKLYJXNLQZWZQC
K2CS6TCX2NDVL2ASEHGP4J4K4IJ6FP3ANNKTSIWVG43HPYSBX6ZQC
UIRWVLX5LDNWURTZOG7EFLXE5OOEL4XBPSLSUHUQSKHC4A7WCVLQC
if (monster->hit_points < 0)
if (monster->hit_points < 1)