--I'm writing this comment because I want to see if I can reproduce that bug.-- Well, I give up. Whether or not I get the error appears to not only depend on t

--I'm writing this comment because I want to see if I can reproduce that bug.-- Well, I give up. Whether or not I get the error appears to not only depend on the text I'm trying to change to, but also the text I'm changing from. It does look like HN is trying to parse the URL, and is unhappy with a URL that ends with the three characters <'".>. But the weird hysteresis... I can't guess. (How on earth am I supposed to quote a string like <'".>?)