Do not initialize fields with default values.

src/Renci.SshNet/Sftp/SftpFileStream.cs

@@ -188,14 +188,9 @@ namespace Renci.SshNet.Sftp
 
             // Initialize the object state.
             _session = session;
-            _bufferPosition = 0;
-            _bufferLen = 0;
-            _bufferOwnedByWrite = false;
             _canRead = ((access & FileAccess.Read) != 0);
             _canSeek = true;
             _canWrite = ((access & FileAccess.Write) != 0);
-            _position = 0;
-            _serverFilePosition = 0;
 
             var flags = Flags.None;
 
@@ -258,7 +253,6 @@ namespace Renci.SshNet.Sftp
 
             if (mode == FileMode.Append)
             {
-                _attributes = _session.RequestFStat(_handle, false);
                 _position = _attributes.Size;
                 _serverFilePosition = (ulong) _attributes.Size;
             }