[luatex] shapemode inside vbox

[Javier Bezos]

I don't understand the logic of the \parshape's in the
plain document below. The problem is the \parshape with
\shapemode=2 (or 3) inside the \vbox. When the line with
'% text' it commented out, it works as I would expect, but
if I uncomment it, the following par with \parshape is
shifted to the left (actually, the 'text' may go after
the \parshape and the result is the same). What's wrong?

Javier

===============================================
\pagedir TRT
\bodydir TRT
\pardir TRT
\textdir TRT

\parindent0pt

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod
tempor incididunt ut labore et dolore magna aliqua.

\hrule

\begingroup

% \pagedir TLT
\bodydir TLT
\pardir TLT
\textdir TLT

\vbox\bgroup

   % text    % uncomment and the following par is shifted to the left

   \parshape 1 .1\hsize .9\hsize \shapemode=2
   Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod
   tempor incididunt ut labore et dolore magna aliqua.

\egroup

\parshape 1 .1\hsize .9\hsize \shapemode=2
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod
tempor incididunt ut labore et dolore magna aliqua.

\endgroup

\bye