In the text format, allow aliases to be defined multiple times, as long
as they're always aliasing the same value.
write.rs is already emitting redundant aliases, because it emits them at
their uses, so this change allows the parser to be able to parse such
code.
* Update to rustfmt-preview.
* Run "cargo fmt --all" with rustfmt 0.4.1.
rustfmt 0.4.1 is the latest release of rustfmt-preview available on the
stable channel.
* Fix a long line that rustfmt 0.4.1 can't handle.
* Remove unneeded commas left behind by rustfmt.
