fix: split out logic

.github/workflows/check-reference.yml

@@ -23,6 +23,12 @@ jobs:
 
       - name: Detect references
         run: |
-          for patch in $(find -name "*.patch"); do
-            git -C "homebrew-core" grep -r "${patch/./}"
+          patches=$(find -name "*.patch")
+          status=0
+          for patch in $patches; do
+            if ! git -C "homebrew-core" grep -r "${patch/./}" > /dev/null; then
+              echo "$patch not needed!"
+              status=1
+            fi
           done
+          exit $status