I have been listening to some data I recorded in Nanning, China, about three years ago. I interviewed 24 undergraduates at Guangxi University, and one pattern I find quite often is the use of 'yes' in answer to a negative question. For example, in the following extract, 'F3' is the Chinese student, while 'Int' is the interviewer (me):
Int: you don’t want to teach in primary school?
And in a further extract, from an interview with another student, 'F8':
Int: you don’t want to be a farmer?
In both of these cases, a native speaker would be more likely to say 'no' to agree with a negative assertion. But use of 'yes' to agree with something is common in New Englishes around the world.
The next example is from a Bruneian speaker, F12 (from page 68 of my book Brunei English: A New Variety in a Multilingual Society, published by Springer; see here):
Int: but you don't remember that now
F12: yes, I don't remember
I predict that this use of 'yes' to agree with a negative assertion will one day become accepted as the norm for international English, regardless of what native speakers like me do.