Macro body gets formatted weirdly

rustfmt formats this macro like this:
```rust
macro_rules! member_mut {
	($self:expr, $member:expr) => {{
		use self::Member::*;
		let r = &mut *$self;
		match $member {
			A => &mut r.a,
			B => &mut r.b,
			}
		}};
}
```
The closing braces are wrongly indented.