boyuanxiao-argondesign authored Oct 15, 2018 and Ronald S. Bultje committed Nov 14, 2018

The first memset is dead code: if primary_ref_frame is
PRIMARY_REF_NONE then segmentation.update_data is always true. The
patch removes this memset and explains why the copy in the other
branch is correct.

The second memset should always fire: if segmentation is not enabled
for this frame, the seg_data structure should be set to zero rather
than copied from a reference frame (see section 5.9.14 of the AV1
spec).