2.8 Cycles GPU (or hybrid) rendering gives result with artefacts. Attached picture shows result of hybrid rendering. Only GPU rendering makes artefacts everywhere on picture.
Used build from https://builder.blender.org/download (Linux 64bit)
Blender 2.79 GPU rendering works properly.
Technically we only accept crash bugs for 2.8, but this is likely also a bug in master builds of 2.79 so it’s ok. For 2.8 non-crash bugs we ask to wait a little longer with reporting.