Auto merge of #4724 - lzutao:minor-appveyor, r=phansch

appveyor: minor syntax change

Use this link to review diff: https://github.com/rust-lang/rust-clippy/pull/4724/files?w=1
changelog: none

appveyor.yml

@@ -1,6 +1,7 @@
 environment:
   global:
     PROJECT_NAME: rust-clippy
+    RUST_BACKTRACE: 1
   matrix:
     #- TARGET: i686-pc-windows-gnu
     #- TARGET: i686-pc-windows-msvc
@@ -15,6 +16,7 @@ branches:
 
 cache:
   - '%USERPROFILE%\.cargo'
+# before cache
 after_test:
   - cargo install -Z install-upgrade cargo-cache --debug
   - cargo cache --autoclean
@@ -22,21 +24,22 @@ after_test:
 install:
   - curl -sSf -o rustup-init.exe https://win.rustup.rs/
   - rustup-init.exe -y --default-host %TARGET% --default-toolchain nightly --profile=minimal
-    - set PATH=%PATH%;C:\Users\appveyor\.cargo\bin
+  - set PATH=%USERPROFILE%\.cargo\bin;%PATH%
+  - rustup component add rustfmt --toolchain nightly & exit 0 # Format test handles missing rustfmt
   - del rust-toolchain
   - cargo install -Z install-upgrade rustup-toolchain-install-master
   - rustup-toolchain-install-master -f -n master -c rustc-dev
-    - rustup component add rustfmt --toolchain nightly & exit 0 # Format test handles missing rustfmt
-    - rustup default master
-    - set PATH=%PATH%;C:\Users\appveyor\.rustup\toolchains\master\bin
+  - rustup override set master
   - rustc -V
   - cargo -V
 
+# Build settings, not to be confused with "before_build" and "after_build".
 build: false
 
-test_script:
-    - set RUST_BACKTRACE=1
+build_script:
   - cargo build --features debugging
+
+test_script:
   - cargo test --features debugging
 
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