pg_archivecleanup, and backup filename to specify as an argument

Hi,

While I'm implementing the patch around pg_archivecleanup, I found
the following warning about pg_archivecleanup in the document.
   Note that the .backup file name passed to the program should not
include the extension.

ISTM that pg_archivecleanup works as expected even if the .backup file
with the extension is specified as follows. So, isn't this warning already
obsolete? Or I'm missing something?

$ pg_archivecleanup -d -x .zip myarchive
000000010000000000000009.00000028.backup.zip
pg_archivecleanup: keep WAL file "myarchive/000000010000000000000009" and later
pg_archivecleanup: removing file "myarchive/000000010000000000000005.zip"
pg_archivecleanup: removing file "myarchive/000000010000000000000003.zip"
pg_archivecleanup: removing file "myarchive/000000010000000000000001.zip"
pg_archivecleanup: removing file "myarchive/000000010000000000000007.zip"
pg_archivecleanup: removing file "myarchive/000000010000000000000006.zip"
pg_archivecleanup: removing file "myarchive/000000010000000000000004.zip"
pg_archivecleanup: removing file "myarchive/000000010000000000000002.zip"
pg_archivecleanup: removing file "myarchive/000000010000000000000008.zip"

Regards,

-- 
Fujii Masao