B doesn't send the same message, there are too many weasel words, and rather than being polite, comes off as giving the other person authority. I think. Here's

B doesn't send the same message, there are too many weasel words, and rather than being polite, comes off as giving the other person authority. I think. Here's how I would phrase it: "Thanks for the patch. How does your code deal with condition X? We're a big project that needs to consider the needs of users under many different circumstances, so even if it seems like X only happens in 1 out of every 10,000 cases, that means it happens every five minutes to one of our users somewhere in the world." The idea is that you know the contributor didn't check for X, but you're giving them the option of saving face. You just asked them whether they considered such a condition and explained why it might be important. Edit: and if they did consider X, they can explain why their solution is okay. You could be wrong in thinking that it's not.