a31eca3fdd
This is a bug in the multithreaded task manager in negative value range. The problem here is that if previter is unsigned, the comparison in the return statement is unsigned, and works incorrectly if stop < 0 && iter >= 0. This in turn can happen if stop is close to 0, because this code is designed to overrun the stop by chunk_size*num_threads as the threads terminate. This probably should go into 2.78 as it prevents a crash.