Use azure condition for rust-src.

Author: ehuss

ci/azure-test-all.yml

@@ -17,10 +17,8 @@ steps:
   displayName: "Install clippy (maybe)"
 
 # This is needed for standard library tests.
-- bash: |
-    if [ "$TOOLCHAIN" = "nightly" ]; then
-      rustup component add rust-src
-    fi
+- bash: rustup component add rust-src
+  condition: and(succeeded(), eq(variables['TOOLCHAIN'], 'nightly'))
   displayName: "Install rust-src (maybe)"
 
 # Deny warnings on CI to avoid warnings getting into the codebase, and note the