BUG #15691: ERROR: XX000: cannot update SecondarySnapshot during a parallel operation

The following bug has been logged on the website:

Bug reference:      15691
Logged by:          zhongkuan fu
Email address:      fuzk80_76@163.com
PostgreSQL version: 10.3
Operating system:   Centos linux 7.4.1708
Description:

I cannot execute the following select sentence and got an error.

postgres=# SELECT
round(cast(coalesce(sum(ST_length(geography(geometry)))/1000,0) as
NUMERIC),4)||'KM' field_value from had_link;

ERROR:  XX000: cannot update SecondarySnapshot during a parallel operation
CONTEXT:  SQL statement "SELECT proj4text FROM public.spatial_ref_sys WHERE
srid = 4326 LIMIT 1"
parallel worker
LOCATION:  GetLatestSnapshot, snapmgr.c:387