simplify code a bit, remove intermediate firstT0/lastT0 vars
simplify code a bit, remove intermediate firstT0/lastT0 vars

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