The memset following the memcpy was silencing the problem since
re-writing that same byte.

Fixes CID1108597, CID1108598, (16x16)
      CID1108599, CID1108600, (8x8)
      CID1108601, CID1108602  (32x32)
Signed-off-by: Clément Bœsch <u@pkh.me>