Duplicate tables found, but it's system tables (information_schema.*, mysql.*)

This configuration runs in MaxScale 2.3.5 but with the error "Duplicate tables found" on 2.3.11. Those duplicate tables are the system tables:

• information_schema.*
• performance_schema.*
• mysql.*
  I must add ignore_databases_regex for resolving the problem:
  [shard-router]
  type=service
  router=schemarouter
  ignore_databases_regex=^((information|performance)_schema|mysql)\..*
  Why those schemas aren't ignored by default?