I built and tested mesa=c2a0600 on g33.  The test provided the
following output, running against the latest drm with gbm back end:

----------------------------------------------------
    </testcase>
    <testcase classname="piglit.spec.!opengl 1_2"
name="texture-packed-formats.g33m64" status="pass" time="0.146700143814">
      <system-out>/tmp/build_root/m64/lib/piglit/bin/texture-packed-formats
-auto
</system-out>
      <system-err>i915: unsupported texture swizzle for format 6
i915: unsupported texture swizzle for format 6
i915: unsupported texture swizzle for format 5
i915: unsupported texture swizzle for format 5
i915: unsupported texture swizzle for format 131
i915: unsupported texture swizzle for format 131
i915: unsupported texture swizzle for format 6
i915: unsupported texture swizzle for format 6
i915: unsupported texture swizzle for format 5
i915: unsupported texture swizzle for format 5
i915: unsupported texture swizzle for format 131
i915: unsupported texture swizzle for format 131
</system-err>
    </testcase>
----------------------------------------------------

status="pass" differs from what was reported in the bug.

I can't bisect further if I can't repro.