Is there any reason why pg_walfile_name() doesn't take timeline change into consideration?

Hi,
I tried on a server that is on timeline 7 now, with .history being:

1 A9/5E0000A0 no recovery target specified
2 127/EB0000A0 no recovery target specified
3 127/F40000A0 no recovery target specified
4 128/170000A0 no recovery target specified
5 188/C70000A0 no recovery target specified
6 7B8/90000A0 no recovery target specified

When I wal file that is "current", i get sensible filename:

=# select pg_walfile_name('800/123');
pg_walfile_name
══════════════════════════
000000070000080000000000
(1 row)

But when I try to find walfile for old lsn, from older timeline, I'm getting bad results:

=# select pg_walfile_name('125/123');
pg_walfile_name
══════════════════════════
000000070000012500000000
(1 row)

Timeline 7 was was "there" when wal lsn was 125/…. Is it just missing
functionality, or am I missing something more complicated?

Best regards,

depesz