Good work, looks like this fix had some unintended side effects. 

Please try the following:

Revert the change without creating a commit, e.g. run "git revert -n
1fb4179f927442354f93dfc8494f0236e50af838".

Then reset the changes to their not added state, e.g. run "git reset HEAD".
This should give you the following list:
M       src/gallium/auxiliary/vl/vl_deint_filter.c
M       src/gallium/auxiliary/vl/vl_idct.c
M       src/gallium/auxiliary/vl/vl_matrix_filter.c
M       src/gallium/auxiliary/vl/vl_median_filter.c
M       src/gallium/auxiliary/vl/vl_mpeg12_bitstream.c
M       src/gallium/auxiliary/vl/vl_vlc.h
M       src/gallium/auxiliary/vl/vl_zscan.c

Now use git checkout on each file (e.g. "git checkout
src/gallium/auxiliary/vl/vl_mpeg12_bitstream.c") to figure out what change
actually broke the decoding.

My best bet is vl_mpeg12_bitstream.c, but could as well be vl_idct.c,
vl_zscan.c or vl_vlc.h.