Zhe,
there are way too many changes in this diff file for anyone to track and
debug.
I suggest you start with a clean gr-trellis and change JUST one block
(say
the viterbi_combined)
and see if this change propagates in python and grc as you expect.
You can also post this change to the list for further feedback (together
with the SIMPLEST possible grc example
that indicates the problem.)
best,
Achilleas