fix(ssh): protect against word splitting

Author: akinomyoga

completions/ssh

@@ -421,7 +421,7 @@ _sftp()
     elif [[ $cur == -* ]]; then
         COMPREPLY=($(compgen -W '$(_parse_usage "$1")' -- "$cur"))
     else
-        _known_hosts_real ${ipvx-} -a ${configfile:+-F "$configfile"} -- "$cur"
+        _known_hosts_real ${ipvx:+"$ipvx"} -a ${configfile:+-F "$configfile"} -- "$cur"
     fi
 } &&
     shopt -u hostcomplete && complete -F _sftp sftp