auto make pr for xla pinned hash (#77824)

see https://docs.google.com/document/d/1jRT-on-v8bcTCHD8aGFH7IuCDR7JL37GlP6Z2EYgmyk/edit#

add file with hash, add nightly job that makes a pr to update the hash, pr needs to be manually accepted (for now? maybe can get bot to approve it automatically later)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/77824
Approved by: https://github.com/janeyx99

.github/workflows/update-xla-commit-hash.yml

@@ -0,0 +1,64 @@
+name: Update xla commit hash
+
+on:
+  schedule:
+    # Every day at 12:37am
+    # Choose a random time near midnight because it may be delayed if there are high loads
+    # See https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#schedule
+    - cron: 37 0 * * *
+  workflow_dispatch:
+
+env:
+  NEW_BRANCH_NAME: update-xla-commit-hash/${{ github.run_id }}-${{ github.run_number }}-${{ github.run_attempt }}
+
+jobs:
+  update-xla-commit-hash:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 1
+          submodules: false
+      - name: Checkout xla
+        shell: bash
+        run: |
+          git clone https://github.com/pytorch/xla.git --depth=1 --quiet
+      - name: Get new commit hash and update file
+        id: update-file
+        shell: bash
+        run: |
+          echo "::set-output name=original_commit::$(cat .github/xla_commit_hash.txt)"
+          pushd xla
+          git rev-parse master > ../.github/xla_commit_hash.txt
+          popd
+          if [[ $(git diff --exit-code .github/xla_commit_hash.txt) ]]; then
+            git checkout -b "${NEW_BRANCH_NAME}"
+            git config --global user.email "pytorchmergebot@users.noreply.github.com"
+            git config --global user.name "PyTorch MergeBot"
+            git add .github/xla_commit_hash.txt
+            git commit -m "update xla commit hash"
+            git push --set-upstream origin "${NEW_BRANCH_NAME}"
+            echo "::set-output name=new_commit::$(cat .github/xla_commit_hash.txt)"
+          fi
+      - name: Create Pull Request
+        uses: actions/github-script@v6
+        if: ${{ steps.update-file.outputs.new_commit }}
+        env:
+          ORIGINAL_COMMIT: ${{ steps.update-file.outputs.original_commit }}
+          NEW_COMMIT: ${{ steps.update-file.outputs.new_commit }}
+        with:
+          script: |
+            const { repo, owner } = context.repo;
+            const { NEW_BRANCH_NAME, NEW_COMMIT, ORIGINAL_COMMIT } = process.env
+            const result = await github.rest.pulls.create({
+              title: '[XLA hash update] update the pinned xla hash',
+              owner,
+              repo,
+              head: `${NEW_BRANCH_NAME}`,
+              base: 'master',
+              body: [
+                'This PR is auto-generated nightly by [this action](https://github.com/pytorch/pytorch/blob/master/.github/workflows/update-xla-commit-hash.yml).\n',
+                `Update the pinned xla hash from \`${ORIGINAL_COMMIT}\` to \`${NEW_COMMIT}\`.`
+              ].join('')
+            });

.github/xla_commit_hash.txt

@@ -0,0 +1 @@
+7f96fbf6f7e37810a805c741416e7c54ae65c8cd

.jenkins/pytorch/common_utils.sh

@@ -100,5 +100,9 @@ function checkout_install_torchvision() {
 function clone_pytorch_xla() {
   if [[ ! -d ./xla ]]; then
     git clone --recursive --quiet https://github.com/pytorch/xla.git
+    pushd xla
+    # pin the xla hash so that we don't get broken by changes to xla
+    git checkout "$(cat ../.github/xla_commit_hash.txt)"
+    popd
   fi
 }