cv::Mat::reshape always returns 1 col (Bug #884)

testcase:

Mat m2;
    Mat mat(4,4,CV_8UC1);
    cout << mat.cols << ", " << mat.rows << std::endl;
    m2 = mat.reshape(16,1);
    cout << m2.cols << ", " << m2.rows << std::endl;
    m2 = mat.reshape(1,16);
    cout << m2.cols << ", " << m2.rows << std::endl;
    m2 = mat.reshape(2,8);
    std::cout << m2.cols << ", " << m2.rows << std::endl;
    m2 = mat.reshape(8,2);
    cout << m2.cols << ", " << m2.rows << std::endl;
result:
4, 4
1, 1
1, 16
1, 8
1, 2

looking at core/src/matrix.cpp, l736, i see that
total_width gets reassigned, thus always leading to a col-count of 1 later.

there seems to be confusion here, whether total_size or total_width
should be used for the recalculation of the cols.