cr2hdr: zebras in shadows

[argv[0]]

I have got the strange result processing Dual-ISO RAW with cr2hdr: shadows in the DNG contains zebras looks like remains of recovery ISO lines from the original RAW.
Please take a look this two RAW(s): 1, 2.
The first one shows this effect in the shadow on top, but the second has no zebras in the same place.
What is it? How to fix it?

BTW, an old 16-bit cr2hdr provides no zebras.

[a1ex]

The algorithm for matching brightness between the two exposures is not robust enough, and so far this is the strongest test case that shows the defect.

Suggestions welcome (something based on robust statistics, of course).

[argv[0]]

As I see this algorithm has implemented by match_exposures function. It's right?

[a1ex]

That's right. You can look back in the commit history to see what approaches I've tried, and you can find here some of the images from my test suite. To debug this process, use --iso-curve as argument.