fix: properly handle github pr merge commits

Author: sublimator

suspicious_patterns.sh

@@ -27,7 +27,10 @@ set -euo pipefail
 exclude_pattern="public_key|not-suspicious"
 
 # Array of filenames to exclude from checking (basename matching)
-exclude_files=("Import_test.cpp")
+exclude_files=(
+  "Import_test.cpp"
+  "validators-example.txt"
+)
 
 # Get the repository's root directory
 repo_root=$(git rev-parse --show-toplevel)
@@ -53,7 +56,17 @@ else
       git fetch --depth=1 origin "$base_ref"
     fi
 
-    files_changed=$(git diff --name-only "origin/$base_ref"...HEAD)
+    # Since there's no merge base in shallow clones, we need to be creative
+    # Save current HEAD, switch to base, then diff the trees
+    current_head=$(git rev-parse HEAD)
+    echo "Comparing against base branch origin/$base_ref..."
+    
+    # Get the tree objects to compare (this works even without shared history)
+    base_tree=$(git rev-parse "origin/$base_ref^{tree}")
+    head_tree=$(git rev-parse "$current_head^{tree}")
+    
+    # Compare the two trees directly
+    files_changed=$(git diff --name-only "$base_tree" "$head_tree")
     mode="PR changes"
   else
     # Regular push event: Check the actual commit that was pushed