fix bad uses of getChunk(0)
fix bad uses of getChunk(0)

replay/metrictank,raintank/raintank-metric,raintank/metrictank,raintank/raintank-metric,OOM-Killer/metrictank,replay/metrictank,replay/metrictank,replay/metrictank,raintank/metrictank,OOM-Killer/metrictank,raintank/metrictank,raintank/raintank-metric,raintank/metrictank,OOM-Killer/metrictank