Log Message:
lftp: updated to 4.9.2

Version 4.9.2
* mkdir: fixed exit code with -f option.
* ftp: made ftp:use-pret setting tri-boolean.
* get/mget/put/mput: don't try next files after error if cmd:fail-exit is true.
* get/mget: fixed -O option with remote URL and xfer:use-temp-file being true.
* mirror: disallow empty patterns; don't delete "..".
* mirror: fixed --on-change with --reverse.
* sftp: fixed a bug with truncated files when packets are reordered (finally).