Create merge-main-into-prs.yml (#2274)

* Create merge-main-into-prs.yml

* Update merge-main-into-prs.yml

.github/workflows/merge-main-into-prs.yml

@@ -0,0 +1,74 @@
+# Ultralytics YOLO 🚀, AGPL-3.0 license
+# Automatically merges repository 'main' branch into all open PRs to keep them up-to-date
+# Action runs on updates to main branch so when one PR merges to main all others update
+
+name: Merge main into PRs
+
+on:
+  workflow_dispatch:
+  # push:
+  #   branches:
+  #     - ${{ github.event.repository.default_branch }}
+
+jobs:
+  Merge:
+    if: github.repository == 'ultralytics/yolov3'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.x"
+          cache: "pip"
+      - name: Install requirements
+        run: |
+          pip install pygithub
+      - name: Merge default branch into PRs
+        shell: python
+        run: |
+          from github import Github
+          import os
+
+          g = Github(os.getenv('GITHUB_TOKEN'))
+          repo = g.get_repo(os.getenv('GITHUB_REPOSITORY'))
+          
+          # Fetch the default branch name
+          default_branch_name = repo.default_branch
+          default_branch = repo.get_branch(default_branch_name)
+          
+          print(f"Default branch for this repository is: {default_branch_name}")
+
+          open_pulls = repo.get_pulls(state='open', sort='created')
+          for pr in open_pulls:
+              try:
+                  # Get full names for repositories and branches
+                  base_repo_name = repo.full_name
+                  head_repo_name = pr.head.repo.full_name
+                  base_branch_name = pr.base.ref
+                  head_branch_name = pr.head.ref
+
+                  # Check if PR is behind the default branch
+                  comparison = repo.compare(default_branch.commit.sha, pr.head.sha)
+                  
+                  if comparison.behind_by > 0:
+                      print(f"PR #{pr.number} ({head_repo_name}:{head_branch_name} -> {base_repo_name}:{base_branch_name}) is behind {default_branch_name} by {comparison.behind_by} commit(s).")
+                      
+                      # Attempt to update the branch
+                      try:
+                          success = pr.update_branch()
+                          assert success, "Branch update failed"
+                          print(f"Successfully merged '{default_branch_name}' into PR #{pr.number} ({head_repo_name}:{head_branch_name} -> {base_repo_name}:{base_branch_name}).")
+                      except Exception as update_error:
+                          print(f"Could not update PR #{pr.number} ({head_repo_name}:{head_branch_name} -> {base_repo_name}:{base_branch_name}): {update_error}")
+                          print("This might be due to branch protection rules or insufficient permissions.")
+                  else:
+                      print(f"PR #{pr.number} ({head_repo_name}:{head_branch_name} -> {base_repo_name}:{base_branch_name}) is up to date with {default_branch_name}.")
+              except Exception as e:
+                  print(f"Could not process PR #{pr.number}: {e}")
+
+        env:
+          GITHUB_TOKEN: ${{ secrets.PERSONAL_ACCESS_TOKEN }}
+          GITHUB_REPOSITORY: ${{ github.repository }}