mv files into a directory the same way you can with cp

[bitfield]

I realise this applies to upstream too: it's a little confusing that you can't mv files into a directory the same way you can with cp:

mkdir new

# works
cp a.txt b.txt new

# doesn't work
mv a.txt b.txt new

-- a.txt --
-- b.txt -- 

Originally posted by @bitfield in #153 (comment)

To be clear, I'm not saying I have a convincing use case for this. It's just that, over many years and hundreds of students, I've developed a nose for what will confuse people trying to learn things.

I can already hear someone asking "Oh, cp works like Unix cp, so mv works like Unix mv?" Oh, my sweet, summer child.

[mvdan]

I agree. Want to send a patch?