This problem came to light due to the chains changes, but effects other code too. It only happens rarely, e.g.,
before this fix:
```
match foo {
MacroArgKind::Delimited(ref delim_tok, ref args) => rewrite_delimited_inner(
delim_tok,
args,
).map(|(lhs, inner, rhs)| format!("{}{}{}", lhs, inner, rhs)),
};
```
after:
```
match foo {
MacroArgKind::Delimited(ref delim_tok, ref args) => {
rewrite_delimited_inner(delim_tok, args)
.map(|(lhs, inner, rhs)| format!("{}{}{}", lhs, inner, rhs))
}
}
```
f0fe9c3c4a