For some reason our reference PNG has an embedded profile called "Color LCD". This seems like an accident, and it breaks the reftest when color management is turned on. I'll put up a patch with the profile stripped off in a few hours.
Created attachment 336749 [details] [diff] [review] fix patch to strip the profile. Reftest passes with CM on and off now.
Created attachment 336754 [details] [diff] [review] updated fix to handle apng issue also Problem also found to exist for APNG test. Adding a fix for that. Vlad told me just to r it myself.
pushed in f3216177949d.