message: explicitly default to nightly
diff: @@ -315,6 +315,7 @@ jobs:
  rustup toolchain install nightly
  rustup target add wasm32-wasi --toolchain nightly
  - run: |
  + rustup default nightly
  make test-wasi-singlepass
  make test-wasi-clif
  - run: rustup default nightly-2019-04-11
  