That's thanks to Bugs Bunny. Nimrod is traditionally the name of a mighty hunter so it made sense for Bugs to call Elmer that to show how far from a mighty hunter he was. But nowadays in the English speaking world we're more likely to think of the Bugs Bunny meaning than the biblical meaning.
It's always hard naming things in a language that isn't your first.
Even in the US, "git" means "idiot." It was my understanding Linus called Git for the same reason Mercurial is called Mercurial: as an unflattering reference to Larry McVoy, who was involved in the Linux/Bitkeeper mess. While typing this though, I discovered that Linux apparently denies this and says it's self-reference. ("I'm an egotistical bastard, and I name all my projects after myself. First 'Linux', now 'Git'".)
Nimrod is actually a little interesting. Until the 1980s, Nimrod was just a Biblical figure, a powerful king/great hunter figure. Possibly because it was used in an ironic sense for bad hunters (perhaps beginning with Elmer Fudd), it came to mean the opposite of its original sense and generalized to "idiot."
Although it honestly wouldn't surprise me if the difference between typing three or five characters to compile is a huge deal in programmer land. Just like how a few tenths of a second of extra loading makes an enormous difference in customer satisfaction with the Google:
When I first heard about Nimrod, I thought of Green Day album "Nimrod" from 1997. Then I thought, why would this language be like a nimrod. Like most, I did not link it with the other literary meaning of "a mighty hunter" hunter.
