feat: add support for closed pull requests with merge true

.github/workflows/test.yml

@@ -176,7 +176,14 @@ jobs:
 
       - name: Run changed-files with a single commit history
         id: changed-files
+        continue-on-error: true
         uses: ./
+
+      - name: Exit with 1 if no error is raised
+        if: github.event_name == 'pull_request' && steps.changed-files.outcome != 'failure'
+        run: |
+          echo "Expected: (failure) got ${{ steps.changed-files.outcome }}"
+          exit 1
 
       - name: Show output
         run: |

action.yml

@@ -66,10 +66,6 @@ inputs:
     description: "Specify a relative path under $GITHUB_WORKSPACE to locate the repository"
     required: false
     default: "."
-  use_fork_point:
-    description: "Finds best common ancestor between two commits to use in a three-way merge as the base_sha"
-    default: "false"
-    required: false
   quotepath:
     description: "Output filenames completely verbatim by setting this to false"
     default: "true"
@@ -201,12 +197,12 @@ runs:
         GITHUB_HEAD_REF: ${{ github.head_ref }}
         GITHUB_ACTION_PATH: ${{ github.action_path }}
         GITHUB_WORKSPACE: ${{ github.workspace }}
+        GITHUB_PULL_REQUEST_BASE_SHA: ${{ github.event.pull_request.base.sha }}
         # INPUT_<VARIABLE_NAME> is not available in Composite run steps
         # https://github.community/t/input-variable-name-is-not-available-in-composite-run-steps/127611
         INPUT_SHA: ${{ steps.sha.outputs.sha }}
         INPUT_BASE_SHA: ${{ steps.base-sha.outputs.base_sha }}
         INPUT_PATH: ${{ inputs.path }}
-        INPUT_USE_FORK_POINT: ${{ inputs.use_fork_point }}
     - name: Glob match
       uses: tj-actions/glob@v13
       id: glob

diff-sha.sh

@@ -96,18 +96,9 @@ else
   echo "::debug::GITHUB_BASE_REF: $TARGET_BRANCH..."
 
   if [[ -z $INPUT_BASE_SHA ]]; then
-    if [[ "$INPUT_USE_FORK_POINT" == "true" ]]; then
-      echo "::debug::Getting fork point..."
-      git fetch --no-tags -u --progress origin "${TARGET_BRANCH}":"${TARGET_BRANCH}" && exit_status=$? || exit_status=$?
-      PREVIOUS_SHA=$(git merge-base --fork-point "${TARGET_BRANCH}" "$(git name-rev --name-only "$CURRENT_SHA")") && exit_status=$? || exit_status=$?
-      echo "::debug::Previous SHA: $PREVIOUS_SHA"
-    else
-      git fetch --no-tags -u --progress origin --depth=1 "${TARGET_BRANCH}":"${TARGET_BRANCH}" && exit_status=$? || exit_status=$?
-      PREVIOUS_SHA=$(git rev-list -n 1 "${TARGET_BRANCH}" 2>&1) && exit_status=$? || exit_status=$?
-      echo "::debug::Previous SHA: $PREVIOUS_SHA"
-    fi
+    PREVIOUS_SHA=$GITHUB_PULL_REQUEST_BASE_SHA && exit_status=$? || exit_status=$?
+    echo "::debug::Previous SHA: $PREVIOUS_SHA"
   else
-    git fetch --no-tags -u --progress origin --depth=1 "$(git rev-parse --verify "$INPUT_BASE_SHA")" && exit_status=$? || exit_status=$?
     PREVIOUS_SHA=$INPUT_BASE_SHA
     TARGET_BRANCH=$(git name-rev --name-only "$PREVIOUS_SHA" 2>&1) && exit_status=$? || exit_status=$?
     echo "::debug::Previous SHA: $PREVIOUS_SHA"