truncate_logs emptied prompt_manager.log through a second open(), leaving the
rotating handler's stream at its old offset: the next record was written past
the new end (zero padding on POSIX) and tell() still reported the old size, so
the file rolled over and resurrected the backup that had just been deleted.
It also logged once per file from inside the deletion loop, which could do the
same with a small size limit. The main log is now truncated through the
handler's own stream and a single summary line is logged afterwards.
Vito Sansevero
f99e76a135