svn 471: ssh password authentication broken

[Timo Juhani Lindfors]

Steps to reproduce:
1) xpra attach ssh:testi1@lindi1:3
2) type "a" without hitting enter

Expected results:
1) xpra shows a password prompt
2) first character of password is read without echo

Actual results:
1) xpra shows

testi1@lindi1's password: using dbusnotify: <class 'dbus.proxies.Interface'>(org.freedesktop.Notifications)
cannot read using ['ssh', '-T', 'testi1@lindi1']: the SSH process has terminated!
'['setxkbmap', '-query']' failed with exit code 255
the server will try to guess your keyboard mapping, which works reasonably well in most cases
however, upgrading 'setxkbmap' to a version that supports the '-query' parameter is preferred
cannot write using ['ssh', '-T', 'testi1@lindi1']: the SSH process has terminated!

2) xpra prints

Permission denied, please try again.
testi1@lindi1's password: 
Permission denied, please try again.
testi1@lindi1's password: 
Permission denied (publickey,password,hostbased).

It seems xpra sends some password to the server even before I have hit enter and it continues sending this password again and again until server gives up.

[Antoine Martin]

r474 fixes this