MAGICK_TIME_LIMIT doesn't work

gistfile1.txt

$ convert --version
Version: ImageMagick 6.8.9-8 Q16 x86_64 2014-10-14 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2014 ImageMagick Studio LLC
Features: DPC OpenMP
Delegates: fontconfig freetype jng jpeg pangocairo png x xml zlib

$ for i in `seq 10`; do time /usr/bin/env  MAGICK_TIME_LIMIT=1s convert test.jpg test.png || echo FAILED; done

real	0m6.919s
user	0m6.648s
sys	0m0.068s

real	0m7.309s
user	0m6.672s
sys	0m0.080s

real	0m7.167s
user	0m6.680s
sys	0m0.072s

convert: time limit exceeded `Operation canceled' @ fatal/cache.c/GetImagePixelCache/1530.
real	0m0.227s
user	0m0.200s
sys	0m0.028s
FAILED

real	0m7.160s
user	0m6.612s
sys	0m0.092s

real	0m7.191s
user	0m6.696s
sys	0m0.068s

real	0m7.189s
user	0m6.656s
sys	0m0.088s

real	0m7.204s
user	0m6.696s
sys	0m0.072s

real	0m7.298s
user	0m6.768s
sys	0m0.064s

real	0m7.281s
user	0m6.776s
sys	0m0.068s