message: sync AppVeyor CI script with Travis
diff: @@ -17,16 +17,21 @@ cache:
  - '%USERPROFILE%\.rustup'
  install:
  + # Compute the rust version we use
  + - set /p RUSTC_HASH=<rust-version
  # Install Rust
  - curl -sSf --retry 3 -o rustup-init.exe https://win.rustup.rs/
  - rustup-init.exe -y --default-host %TARGET% --default-toolchain stable
  - set PATH=%USERPROFILE%\.cargo\bin;%PATH%
  + - rustup default stable
  + - rustup uninstall beta
  + - rustup update
  # Install "master" toolchain
  - cargo install rustup-toolchain-install-master & exit 0
  - - set /p RUSTC_HASH=<rust-version
  - rustup-toolchain-install-master -f -n master %RUSTC_HASH% -c cargo -c rust-src
  - rustup default master
  - rustc --version
  + - cargo --version
  build_script:
  - set RUSTFLAGS=-C debug-assertions
  