fix: remove racy branch existence check in CLI coverage workflow

The clone step used `git ls-remote` then `git fetch` as separate
operations, which fails when the branch is deleted between the two
calls (e.g. right after a PR merge). Replace with a single `git fetch`
whose exit code tells us whether the branch exists.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: rgarcia

.github/workflows/update-cli-coverage.yml

@@ -93,19 +93,16 @@ jobs:
         run: |
           gh repo clone kernel/kernel /tmp/kernel-api -- --depth=1
 
-      - name: Clone CLI repo and checkout existing branch
+      - name: Clone CLI repo
         env:
           GH_TOKEN: ${{ steps.app-token.outputs.token }}
         run: |
           gh repo clone kernel/cli /tmp/kernel-cli
           cd /tmp/kernel-cli
           
-          # Check if the cli-coverage-update branch already exists on remote
-          if git ls-remote --exit-code --heads origin cli-coverage-update >/dev/null 2>&1; then
+          if git fetch origin cli-coverage-update 2>/dev/null; then
             echo "Branch cli-coverage-update exists, checking it out..."
-            git fetch origin cli-coverage-update
             git checkout cli-coverage-update
-            # Merge latest main to keep it up to date
             git merge origin/main -m "Merge main into cli-coverage-update" --no-edit || true
           else
             echo "Branch cli-coverage-update does not exist, will create from main"
@@ -290,10 +287,10 @@ jobs:
           # Output Format
           After pushing changes, create or update an evergreen PR using gh:
 
-          1. Check if a PR already exists for the cli-coverage-update branch:
-             gh pr list --repo kernel/cli --head cli-coverage-update --json number
+          1. Check if an open PR already exists for the cli-coverage-update branch:
+             gh pr list --repo kernel/cli --head cli-coverage-update --state open --json number
 
-          2. If PR exists, update it. If not, create a new one.
+          2. If an open PR exists, update it. If not, create a new one.
 
           If new commands or flags were added:
             Title: 'CLI: Update SDK to <version> and add new commands/flags'