Fix race in SeriesN and CreateSeriesIfNotExists
Fix race in SeriesN and CreateSeriesIfNotExists

mark-rushakoff/influxdb,vladlopes/influxdb,mark-rushakoff/influxdb,runner-mei/influxdb,influxdata/influxdb,influxdb/influxdb,benbjohnson/influxdb,li-ang/influxdb,linearb/influxdb,vladlopes/influxdb,chenziliang/influxdb,influxdb/influxdb,linearb/influxdb,chenziliang/influxdb,li-ang/influxdb,benbjohnson/influxdb,archsaber/influxdb,nooproblem/influxdb,vladlopes/influxdb,mark-rushakoff/influxdb,archsaber/influxdb,runner-mei/influxdb,nooproblem/influxdb,mark-rushakoff/influxdb,chenziliang/influxdb,linearb/influxdb,influxdata/influxdb,benbjohnson/influxdb,nooproblem/influxdb,chenziliang/influxdb,influxdb/influxdb,mark-rushakoff/influxdb,influxdb/influxdb,vladlopes/influxdb,archsaber/influxdb,influxdb/influxdb,runner-mei/influxdb,mark-rushakoff/influxdb,benbjohnson/influxdb,linearb/influxdb,linearb/influxdb,nooproblem/influxdb,archsaber/influxdb,influxdb/influxdb,nooproblem/influxdb,runner-mei/influxdb