Bug#369401: openssh-client: SenvEnv misses possibility to reset/override/disable previous settings

[Julien Palard <julien@palard.fr>]

    Hi!
    
    According to
    https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=573316 this has
    been closed thanks to a `-` prefix, like:
    
        SendEnv -LANG
    
    This is documented in manpage:
    
        $ man ssh_config | grep -A1 'clear previously set SendEnv'
                   It is possible to clear previously set SendEnv
    variable names by prefixing patterns with  -.   The  de‐
                   fault is not to send any environment variables.
    
    But it looks like it does not works:
    
        $ cat ~/.ssh/config
        SendEnv -LANG -LC_ALL
    
        $ ssh -vvv mdk@test-machine env 2>&1 | grep LC_ALL
        debug1: channel 0: setting env LC_ALL = "fr_FR.UTF-8"
        bash: warning: setlocale: LC_ALL: cannot change locale
    (fr_FR.UTF-8)
        LC_ALL=fr_FR.UTF-8
    
    Bests,
-- 
[Julien Palard](https://mdk.fr)