Fix AST rewriting panic due to a nil Condition.
Fix AST rewriting panic due to a nil Condition.

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