Re: Unrecognized exception condition "deprecated_feature"

For some reason using an error code of 'deprecated_feature' does not work, while its equivalent '01P01' works just fine.

kouber=# DO $$ 

BEGIN 

 RAISE WARNING 'Deprecated' 

   USING ERRCODE = 'deprecated_feature'; 

END; 

$$; 

ERROR:  unrecognized exception condition "deprecated_feature" 

CONTEXT:  PL/pgSQL function inline_code_block line 3 at RAISE

kouber=# DO $$ 

BEGIN 

 RAISE WARNING 'Deprecated' 

   USING ERRCODE = '01P01';              

kouber@spectre:~/src/postgres$ grep -r deprecated_feature .                 

./src/backend/utils/errcodes.txt:01P01    W    ERRCODE_WARNING_DEPRECATED_FEATURE                             deprecated_feature

I am using PostgreSQL 10.1, I apologize in case it has already been fixed in 10.2 or 10.3.