bug#21221: guile-2.2 socket ports used with display does not send utf8 !

[Linas Vepstas <linasvepstas@gmail.com>]

The following simple client-server program fails for me.
For simplicity, for the server, just use netcat listening on port 7777:

$ nc -l 7777

In a guile shell, try this:
(setlocale LC_ALL "")
(define sss (socket PF_INET SOCK_STREAM 0))
(set-port-encoding! sss "utf-8")
(connect sss AF_INET (inet-pton AF_INET "127.0.0.1") 7777)
(set-port-encoding! sss "utf-8")
(display "SmålandSmåland\n" sss)
(close-port sss)


The SmålandSmåland gets corrupted:  nc receives Sm?landSm?land

Some types of utf8 do go through, so e.g. (display "Ćićolina\n" sss)
seems to work fine.  This finish/norweign thing, though, fails,
vietnamese too.
(display "Hòa Phú Phú Tân Hiệp An  Tương Bình Hiệp Định Hòa\n" sss)

I suppose the answer is "don't use display for sending strings on a
socket", but I'm stumped as to why there should even be an encoding
error, why its not utf8 end-to-end.

This is for guile-2.2 from a recent git pull of the master source from
about June 2015, but I believe the problem occurs on guile-2.0 as
well.

guile --version
guile (GNU Guile) 2.1.0.305-e7097-dirty

this is on ubuntu 14.04 aka ubuntu trusty

-- Linas Vepstas