Neither is present in my project and i checked out the same revision on both machines. By moving `rust-toolchain.toml` out of the way, I'm getting back the same result on both targets. But strangely enough even the nightly toolchain selected by this file is the same on both machines.

There seems to be [an issue](https://github.com/rust-lang/rustfmt/issues/5964) with rustfmt 1.7.0-nightly. And maybe `~/.cargo/bin/rustfmt` dispatches to the actually selected toolchain.
```
$ rustfmt +stable --check src/*
```
gives a consistent report on both systems while the nightly version does not. Trap for young players ...