The sieve-manage package uses the managesieve protocol (s.
https://datatracker.ietf.org/doc/html/draft-ietf-sieve-managesieve) to
communicate with a sieve server process.

When the sieve-manage client retrieves a script from the server it uses
the `sieve-manage-getscript' function to send command `GETSCRIPT
"<scriptname>"<CRLF>` to the server and tries to parse the response.

If the downloaded sieve script contains multibyte characters the attempt
to parse the response results in an infloop (in
`sieve-manage-parse-okno').

To reproduce, save the following code