"where" filter with not equal (!=) did't work

__Steps to reproduce:__
List the minimal actions needed to reproduce the behavior.
No error log. But start from zero clock +0 time zone. Solved by restart influxdb server.

__Expected behavior:__
Describe what you expected to happen.
exception!='None' must return without 'None' series.
> SELECT * FROM "http_request" WHERE (source_ip='10.9.15.49' AND exception!='None') AND time >= now() - 3m
name: http_request
time exception pid source_app source_ip target_app target_ip value
---- --------- --- ---------- --------- ---------- --------- -----

__Actual behavior:__
Describe What actually happened.
return 'None' series.
> SELECT * FROM "http_request" WHERE (source_ip='10.9.15.49' AND exception!='None') AND time >= now() - 3m
name: http_request
time exception pid source_app source_ip target_app target_ip value
---- --------- --- ---------- --------- ---------- --------- -----
1577930100000000000 None api 10.9.15.49 dc 10.42.109.93 184
1577930100000000000 None api 10.9.15.49 dc 10.42.28.161 53
1577930100000000000 None api 10.9.15.49 dc 10.42.116.37 178

__Environment info:__
centos 7.1 32C64G
and influxdb1.7.8

__Config:__
tsi1

__Logs:__
No error log. But start from zero clock +0 time zone. Solved by restart influxdb server.

Start by reproducing the SELECT query against InfluxDB 1.7.8 on a tsi1 configuration, using the reported source_ip, exception, time range, and UTC setting. Compare results before and after restarting the server; done means exception!='None' excludes the None series without requiring a restart.

Written by the indexing model from the issue text.