title: sshfs with different gid on remote
body: <p>I don't know how to mount a remote directory
  "remote_dir" on computer "remote", having remote gid "wgrp".
  Help is welcome.</p>
  
  <pre>
    me@local$ sshfs me@remote:/remote_dir remote_as_wgrp ...wanted_options...
  </pre>
  
  <p>A workaround is to create a new user "me_wgrp" belonging to group "wgrp".
  But the problem seems conceptually so simple that I'm sure there is a solution.</p>
  
  <p>Context:<br>
  I'm able to connect using ssh on remote compute, and then to change my gid:</p>
  
  <pre>
    me@local$ ssh me@remote
    me@remote$ newgrp wgrp
  </pre>
  
  <p>Now I can create files in directories which are only writable by the group "wgrp".</p>
  
  <p>I have tried </p>
  
  <pre>
    sshfs me@remote:/remote_dir remote_as_wgrp -o ssh_command='newgrp wgrp'
  </pre>
  
  <p>but sshfs seems blocked.</p>
  
  <p>Also, if I try</p>
  
  <pre>
    ssh me@remote 'newgrp wgrp'
  </pre>
  
  <p>ssh doesn't give the prompt, but it accepts commands.</p>