* PSDImagePlugin did not sanity check the number of input layers and
vs the size of the data block, this could lead to a DOS on
Image.open prior to Image.load.
* This issue dates to the PIL fork
- Make is_animated APNG behavior consistent with other Pillow formats
- is_animated will be true when n_frames is greater than 1 (for APNG
this depends on animation frame count + presence or absence of a
default image)
