[1.2 regression] Selecting specific field from multiple RP's fails

[kostasb]

influxdb_1.2.1~rc5

Repro case:

> create database db1 
> create retention policy rp1 on db1 duration 1w replication 1 default 
> create retention policy rp2 on db1 duration 1w replication 1 
> insert data,tag=1 value=1 
> insert data,tag=1 value=2
> insert data,tag=1 value=3
> select value from "db1"."rp1"."data"
name: data
time                value
----                -----
1488386247311798839 1
1488386257727415986 2
1488386259318734453 3
> select value from "db1"."rp1"."data","db1"."rp2"."data" 
> 

(select * works)
> select * from "db1"."rp1"."data","db1"."rp2"."data" 
name: data
time                tag value
----                --- -----
1488386247311798839 1   1
1488386257727415986 1   2
1488386259318734453 1   3


...

downgrade to 1.1.1:

> select value from "db1"."rp1"."data","db1"."rp2"."data" 
name: data
time			value
----			-----
1488386247311798839	1
1488386257727415986	2
1488386259318734453	3

[jsternberg]

Fixed via #8079.