Something is going very wrong with this job: it says that the rustc version is
rustc 1.46.0-nightly (4fb54ed48 2020-06-14), which is 1 week outdated, but at the same time
rustup update says
nightly-x86_64-unknown-linux-gnu unchanged - rustc 1.46.0-nightly (a8cf39911 2020-06-21)
To me it looks like whatever caching travis is doing when I say
- rust: nightly has gone seriously wrong.