BUG #15942: not working function pg_stat_file

The following bug has been logged on the website:

Bug reference:      15942
Logged by:          Michal C
Email address:      c_michal@poczta.onet.pl
PostgreSQL version: 11.4
Operating system:   Microsoft Windows [Version 10.0.18362.267]
Description:

Sorry my English is horribile.
my PG version is "PostgreSQL 11.4, compiled by Visual C++ build 1914,
64-bit"

I create 2 GB file:
show data_directory; 
Result: "D:/pg_data"

copy (select

to_char(number,'0.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000')
from generate_series(1,1024*1024*2,1) d(number))
to 'D:\pg_data\my_data_01.txt';

and reading information about file:

with files as (select * from pg_ls_dir('.') f(file) where file ilike
'my_data_01.txt')
, files_info as (select file, (pg_stat_file(file)).* from files)
select * from files_info;

and result is:
> ERROR:  could not stat file "my_data_01.txt": Unknown error
> SQL state: XX000

When I run the script on PG 10.9 on the same computer, everything works
fine.