It's entirely possible for an evildoer to make someone feel bad while remaining completely polite.
First send a message to the mailing list as "Alice" providing a detailed bug report for a real bug, and a flawless patch to fix it.
Then you reply to the mailing list as "Bob" agreeing that it's a bug, thanking "Alice" for the patch and the time she spent producing such a detailed bug report, then explaining that unfortunately it won't be merged any time soon, then apologising and saying you know how frustrating it must be for Alice.
Your two characters have been model citizens: Alice has contributed a good quality bug report, and code. Bob has helped the project by confirming bug reports, and has never been rude or critical - merely straightforward, realistic and a bit overly polite.
As someone else said in this thread, scammers are often rude, because it makes people act fast, polite responses give them time to think. Of course, people are very easily manipulated. But by completely rejecting rudeness and having the mindset to not let others put pressure on me, you will improve the odds by a lot.
First send a message to the mailing list as "Alice" providing a detailed bug report for a real bug, and a flawless patch to fix it.
Then you reply to the mailing list as "Bob" agreeing that it's a bug, thanking "Alice" for the patch and the time she spent producing such a detailed bug report, then explaining that unfortunately it won't be merged any time soon, then apologising and saying you know how frustrating it must be for Alice.
Your two characters have been model citizens: Alice has contributed a good quality bug report, and code. Bob has helped the project by confirming bug reports, and has never been rude or critical - merely straightforward, realistic and a bit overly polite.