[beta-1.91] chore: Disabled reserved_windows_name test temporaily (#16050)

Beta backports
- e906ad9 (ignoring
flaky test otherwise it sometimes fails rust-lang/rust beta backport)

In order to make CI pass, the following PRs are also cherry-picked:

- b6d572b
- c249c45

Author: epage

.github/workflows/main.yml

@@ -276,6 +276,7 @@ jobs:
     - run: rustup update nightly && rustup default nightly
     - run: rustup update stable
     - run: rustup component add rust-docs
+    - run: rustup component add rustfmt --toolchain stable
     - run: ci/validate-man.sh
     # This requires rustfmt, use stable.
     - name: Run semver-check

tests/build-std/main.rs

@@ -396,7 +396,9 @@ fn test_proc_macro() {
 }
 
 #[cargo_test(build_std_real)]
-fn test_panic_abort() {
+fn default_features_still_included_with_extra_build_std_features() {
+    // This is a regression test to ensure when adding extra `build-std-features`,
+    // the default feature set is still respected and included.
     // See rust-lang/cargo#14935
     let p = project()
         .file(
@@ -413,7 +415,7 @@ fn test_panic_abort() {
     p.cargo("check")
         .build_std_arg("std,panic_abort")
         .env("RUSTFLAGS", "-C panic=abort")
-        .arg("-Zbuild-std-features=panic_immediate_abort")
+        .arg("-Zbuild-std-features=optimize_for_size")
         .run();
 }
 

tests/testsuite/package.rs

@@ -2934,7 +2934,9 @@ src/lib.rs
         .run();
 }
 
-#[cargo_test]
+#[cargo_test(
+    ignore_windows = "temporarily disabling due to flakiness: https://rust-lang.zulipchat.com/#narrow/channel/246057-t-cargo/topic/reserved_windows_name.20test.20failing/with/543085230"
+)]
 #[cfg(windows)]
 fn reserved_windows_name() {
     // If we are running on a version of Windows that allows these reserved filenames,