Bug in OpenCL driver on Intel HD Graphics?

Hello. 

I found a curious bug in Intel OpenCL driver on Intel HD Graphics 4600 (Core i5 4570). 

Driver version: 10.18.10.3412

Intel OpenCL SDK Version: 2013 R3 64-bit

I write following kernel:

    int gidx = get_global_id(0);
    int gidy = get_global_id(1);
    
    __local uchar temp[3];
    uchar r = 255;
    if (gidx == 0 && gidy == 0)
    {
        temp[0] = 255;
        temp[1] = 34;
        temp[2] = 255;
        for (int i=0; i<3; i++)
        {
            printf("temp[i] = %d\n", temp[i]);
            printf("r = %d\n", r);
            r = min(r,temp[i]);
        }
    }

When I run it I get:

temp[i] = 255
r = 255
temp[i] = 34
r = 15
temp[i] = 255
r = 15

Variable 'r' have incorrect value (15 instead 34). What may cause the problem?