Fix jq error and master not found issue

.github/workflows/rustc.yml

@@ -30,4 +30,6 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Run rustc script
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: ./scripts/check_rustc.sh

scripts/check_rustc.sh

@@ -46,12 +46,25 @@ cd "$REPO_DIR"
 # Get the commit ID from rustc --version
 echo "Retrieving commit ID..."
 COMMIT_ID=$(rustc --version | sed -e "s/.*(\(.*\) .*/\1/")
-echo "$COMMIT_ID for rustc is"
 
 # Get the full commit ID for shallow clone
-curl -H "Connection: close" -o "${TMP_RUST_DIR}/output.json" -s --show-error \
-    "https://api.github.com/repos/rust-lang/rust/commits?sha=${COMMIT_ID}&per_page=1"
-COMMIT_ID=$(jq -r '.[0].sha' "${TMP_RUST_DIR}/output.json")
+echo "Full commit id for $COMMIT_ID for is:"
+
+if [ -z "${GH_TOKEN:-}" ]; then
+  curl -o "${TMP_RUST_DIR}/output.json" -s --show-error \
+      "https://api.github.com/repos/rust-lang/rust/commits?sha=${COMMIT_ID}&per_page=1"
+else
+  # Use token if possible to avoid being throttled
+  curl -o "${TMP_RUST_DIR}/output.json" -s --show-error \
+       --request GET \
+       --url "https://api.github.com/repos/rust-lang/rust/commits?sha=${COMMIT_ID}&per_page=1" \
+       --header "Accept: application/vnd.github+json" \
+       --header "Authorization: Bearer $GH_TOKEN"
+fi
+cat "${TMP_RUST_DIR}/output.json"  # Dump the file in case `curl` fails.
+
+COMMIT_ID=$(cat "${TMP_RUST_DIR}/output.json" | jq -r '.[0].sha')
+echo "- $COMMIT_ID"
 
 # Clone the rust-lang/rust repository
 echo "Cloning rust-lang/rust repository into ${TMP_RUST_DIR}..."
@@ -74,6 +87,8 @@ cp -r "${REPO_DIR}/library" "${TMP_RUST_DIR}"
 pushd "${TMP_RUST_DIR}"
 ./configure --set=llvm.download-ci-llvm=true
 export RUSTFLAGS="--check-cfg cfg(kani) --check-cfg cfg(feature,values(any()))"
+export RUST_BACKTRACE=1
+unset GITHUB_ACTIONS # Bootstrap script requires specific repo layout when run from an action. Disable that.
 
 # Run tidy
 if [ "${TIDY_MODE}" == "--bless" ];