Make sure to actually use the toolchain specified

Author: Xanewok

ci/azure-install-rust.yml

@@ -2,7 +2,10 @@ steps:
   # Linux and macOS.
   - script: |
       set -e
-      curl https://sh.rustup.rs -sSf | sh -s -- -y --default-toolchain $RUSTUP_TOOLCHAIN
+      curl https://sh.rustup.rs -sSf | sh -s -- -y --default-toolchain none
+      export PATH=$PATH:$HOME/.cargo/bin
+      rustup toolchain install $RUSTUP_TOOLCHAIN
+      rustup default $RUSTUP_TOOLCHAIN
       echo "##vso[task.setvariable variable=PATH;]$PATH:$HOME/.cargo/bin"
     env:
       RUSTUP_TOOLCHAIN: ${{parameters.rust_version}}
@@ -11,18 +14,20 @@ steps:
 
   # Windows.
   - script: |
-      echo "windows"
       curl -sSf -o rustup-init.exe https://win.rustup.rs
-      rustup-init.exe -y --default-toolchain %RUSTUP_TOOLCHAIN%
+      rustup-init.exe -y --default-toolchain none
       set PATH=%PATH%;%USERPROFILE%\.cargo\bin
+      rustup toolchain install %RUSTUP_TOOLCHAIN%
+      rustup default %RUSTUP_TOOLCHAIN%
       echo "##vso[task.setvariable variable=PATH;]%PATH%;%USERPROFILE%\.cargo\bin"
     env:
       RUSTUP_TOOLCHAIN: ${{parameters.rust_version}}
-    displayName: Install rust (windows)
+    displayName: "Install rust (windows)"
     condition: eq(variables['Agent.OS'], 'Windows_NT')
 
   # All platforms.
   - script: |
+        rustup toolchain list
         rustc -Vv
         cargo -V
     displayName: Query rust and cargo versions