[Bf-committers] Alpha clamping in render layers node

[gespertino at gmail.com]

Nevermind: Even if it cancels the negative values in alpha=0 regions
there will be still negative values in AA pixels in solid regions, so
it won't make much difference and FSA will be the right way to go
anyway.
It still feels odd that those negative values can end up in the
destination file. You can clamp alpha and that's ok, but what happens
with those AA values from passes in solid areas? Should you clamp them
too?