Mat.copyTo with mask broken (Bug #1918)

there is a bug in copyTo, when using a mask - an assertion fails.

Here is the sample code that fails:

#include <opencv2/core/core.hpp>
void main() {
cv::Mat_<unsigned char> tmpSrc(100,100);
tmpSrc = 124;
cv::Mat_<unsigned char> tmpMask(100,100);
tmpMask = 255;
cv::Mat_<unsigned char> tmpDst(100,100);
tmpDst = 2;
tmpSrc.copyTo(tmpDst,tmpMask);
}

I've tried initializing everything, but still no dice.

One one end, I've found a problem in
void _OutputArray::create(int dims, const int* size, int type, int i, bool allowTransposed, int fixedDepthMask) const

see the code below

if(fixedType())
{
            if(CV_MAT_CN(type) == m.channels() && ((1 << CV_MAT_TYPE(flags)) & fixedDepthMask) != 0 )
                type = m.type();
            else
                CV_Assert(!fixedType() || (CV_MAT_CN(type) == m.channels() && ((1 << CV_MAT_TYPE(flags)) & fixedDepthMask) != 0));
        }

Basically if it will ever go into the else, it will always fail, because you have something like

if(A) {
if (B)
bla();
else{
// it got here, so we have A && !B
assert(!A || B); // this will fail
}
}

I looked in how copyTo works if there is no mask, and there is a special case for creating the destination OutputArray if the dimension is 2, so I've copied that here as well..see in the proposed patch. I might not be the best solution, but it's got me over the problem.