Bump actions/checkout from 5.0.0 to 6.0.0 (#157)

Bumps [actions/checkout](https://github.com/actions/checkout) from 5.0.0 to 6.0.0.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](08c6903cd8...1af3b93b68)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: 6.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/ci.yml

@@ -51,7 +51,7 @@ jobs:
 
     steps:
       - name: Checkout Example.jl
-        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6.0.0
         with:
           repository: julia-actions/Example.jl
 
@@ -60,7 +60,7 @@ jobs:
         shell: bash
 
       - name: Checkout julia-runtest
-        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6.0.0
         with:
           path: ./.github/actions/julia-runtest
 

.github/workflows/test_logger_ci.yml

@@ -51,7 +51,7 @@ jobs:
 
     steps:
       - name: Checkout julia-runtest
-        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6.0.0
 
       - uses: julia-actions/setup-julia@5c9647d97b78a5debe5164e9eec09d653d29bd71 # v2.6.1
         with:

test_harness.jl

@@ -25,8 +25,16 @@ if haskey(ENV, "GITHUB_SHA") && get(ENV, "GITHUB_EVENT_NAME", "") == "pull_reque
 
         # Check if there's any difference between the merge commit and the PR head
         # In GitHub Actions, HEAD^2 is the PR head (second parent of merge commit)
-        # success() returns true if the command exits with 0 (no differences)
+        # First check if HEAD^2 exists (i.e., this is actually a merge commit)
-        has_diff = !success(`git diff --quiet --exit-code HEAD^2 HEAD`)
+        if success(`git rev-parse --verify --quiet HEAD^2`)
+            # Compare tree hashes to check if content actually differs
+            merge_tree = chomp(read(`git rev-parse HEAD^\{tree\}`, String))
+            pr_tree = chomp(read(`git rev-parse HEAD^2^\{tree\}`, String))
+            has_diff = merge_tree != pr_tree
+        else
+            # Not a merge commit, so no difference to report
+            has_diff = false
+        end
 
         if has_diff
             base_branch = isempty(base_branch_name) ? "the base branch" : "'$base_branch_name'"