The node_keying_matte.blend test is very sensitive to the exact
pixel values in the input image. It is hard to match the output
between SSE and non-SEE codepaths of sRGB-to-linear conversion,
especially when it is done form the OCIO side.
Note that even without OCIO the match could be very difficult to
achieve, since BLI also implements SSE optimization (although, we
are in better control over there, so might increase the accuracy).
Ref #110685
Pull Request: https://projects.blender.org/blender/blender/pulls/110897
af101ad3f8