Started with:

commit fbb423b43380d0e43d14056e96846da412693148
Author: Grazvydas Ignotas <notasas@gmail.com>
Date:   Thu Sep 3 01:54:28 2015 +0300

    r600g: apply disable workaround on all scissors

    During review of the "r600g: make all scissor states use single atom" patch
    Marek Olšák noticed that scissor disable workaround should be applied on
    all scissor states and not just first one, so let's do so.

    Signed-off-by: Marek Olšák <marek.olsak@amd.com>

Reverting the commit above fixes the issue.