Rework dependency updates to avoid force pushing. (#852)

See iree-org/iree-turbine#397 for details. This
has the same changes, but using `shark-pr-automator[bot]
<41898282+github-actions[bot]@users.noreply.github.com>` instead of
`iree-pr-automator[bot] <[email protected]>` as the
commit author.

---------

Co-authored-by: Marius Brehler <[email protected]>

.github/workflows/update_iree_requirement_pins.yml

@@ -8,6 +8,11 @@ name: Update IREE requirement pins
 
 on:
   workflow_dispatch:
+    inputs:
+      branch-name:
+        default: "integrates/iree"
+        type: string
+        description: The branch name to put updates on
   schedule:
     # Weekdays at 11:00 AM UTC = 03:00 AM PST / 04:00 AM PDT
     - cron: "0 11 * * 1-5"
@@ -16,45 +21,76 @@ permissions:
   contents: write
   pull-requests: write
 
+env:
+  GIT_BRANCH_NAME: ${{ inputs.branch-name || 'integrates/iree' }}
+
 jobs:
-  update-iree:
+  check-for-existing-branch:
     if: ${{ github.repository_owner == 'nod-ai' || github.event_name != 'schedule' }}
     runs-on: ubuntu-24.04
+    outputs:
+      branch-exists: ${{ steps.check-exists.outputs.branch-exists }}
 
     steps:
-      - uses: actions/create-github-app-token@c1a285145b9d317df6ced56c09f525b5c2b6f755 # v1.11.1
-        id: generate-token
-        with:
-          app-id: ${{ secrets.CREATE_PULL_REQUEST_TOKEN_APP_ID }}
-          private-key: ${{ secrets.CREATE_PULL_REQUEST_TOKEN_APP_PRIVATE_KEY }}
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - name: Check for existing integrate branch
+        id: check-exists
+        run: |
+          BRANCH_EXISTS=$(git ls-remote --exit-code --heads origin ${{ env.GIT_BRANCH_NAME }} | wc -l)
+          echo branch-exists=${BRANCH_EXISTS} >> "${GITHUB_OUTPUT}"
+          if [[ ${BRANCH_EXISTS} == 1 ]]; then
+            echo "Skipping update PR creation since the `${{ env.GIT_BRANCH_NAME }}` branch already exists." >> ${GITHUB_STEP_SUMMARY}
+          fi
+
+  update-iree:
+    needs: check-for-existing-branch
+    runs-on: ubuntu-22.04
+    if: ${{ needs.check-for-existing-branch.outputs.branch-exists == 0 }}
 
+    steps:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
 
       - name: "Setting up Python"
         uses: actions/setup-python@0b93645e9fea7318ecaed2b359559ac225c90a2b # v5.3.0
         with:
           python-version: 3.11
 
-      # This sets a few environment variables used below.
+      # This sets a few environment variables via GITHUB_ENV.
       - name: Update IREE requirement pins
         run: build_tools/update_iree_requirement_pins.py
 
+      - uses: actions/create-github-app-token@c1a285145b9d317df6ced56c09f525b5c2b6f755 # v1.11.1
+        if: ${{ env.CREATE_PULL_REQUEST_TOKEN_APP_ID != '' && env.CREATE_PULL_REQUEST_TOKEN_APP_PRIVATE_KEY != '' }}
+        id: generate-token
+        with:
+          app-id: ${{ secrets.CREATE_PULL_REQUEST_TOKEN_APP_ID }}
+          private-key: ${{ secrets.CREATE_PULL_REQUEST_TOKEN_APP_PRIVATE_KEY }}
+        env:
+          CREATE_PULL_REQUEST_TOKEN_APP_ID: ${{ secrets.CREATE_PULL_REQUEST_TOKEN_APP_ID }}
+          CREATE_PULL_REQUEST_TOKEN_APP_PRIVATE_KEY: ${{ secrets.CREATE_PULL_REQUEST_TOKEN_APP_PRIVATE_KEY }}
+
       - name: Create or update pull request
         if: |
           ${{ env.CURRENT_IREE_BASE_COMPILER_VERSION }} != ${{ env.LATEST_IREE_BASE_COMPILER_VERSION }} || \
           ${{ env.CURRENT_IREE_BASE_RUNTIME_VERSION }} != ${{ env.LATEST_IREE_BASE_RUNTIME_VERSION }} || \
           ${{ env.CURRENT_IREE_TURBINE_VERSION }} != ${{ env.LATEST_IREE_TURBINE_VERSION }}
           ${{ env.CURRENT_SHORTFIN_IREE_GIT_TAG }} != ${{ env.LATEST_SHORTFIN_IREE_GIT_TAG }}
+        id: cpr
         uses: peter-evans/create-pull-request@67ccf781d68cd99b580ae25a5c18a1cc84ffff1f # v7.0.6
         with:
-          token: ${{ steps.generate-token.outputs.token }}
+          token: ${{ steps.generate-token.outputs.token || secrets.GITHUB_TOKEN }}
           base: main
-          branch: integrates/iree
-          delete-branch: true
+          branch: ${{ env.GIT_BRANCH_NAME }}
+          author: shark-pr-automator[bot] <41898282+github-actions[bot]@users.noreply.github.com>
           signoff: true
           title: "Bump IREE requirement pins to their latest versions."
           body: |
             Diff: https://github.com/iree-org/iree/compare/iree-${{ env.CURRENT_IREE_BASE_COMPILER_VERSION }}...iree-${{ env.LATEST_IREE_BASE_COMPILER_VERSION }}
 
             Auto-generated by GitHub Actions using [`.github/workflows/update_iree_requirement_pins.yml`](https://github.com/${{ github.repository }}/blob/main/.github/workflows/update_iree_requirement_pins.yml).
           commit-message: "Bump IREE to ${{ env.LATEST_IREE_BASE_COMPILER_VERSION }}."
+
+      - name: Write summary
+        if: ${{ steps.cpr.outputs.pull-request-number }}
+        run: |
+          echo "Pull Request URL: ${{ steps.cpr.outputs.pull-request-url }}" >> ${GITHUB_STEP_SUMMARY}