Checkout the PR when triggering try from PR comments (#30069)

Fixes #30067.

.github/workflows/linux-wpt.yml

@@ -25,8 +25,16 @@ jobs:
         chunk_id: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
     steps:
       - uses: actions/checkout@v3
+        if: github.event_name != 'issue_comment'
         with:
           fetch-depth: 2
+      # This is necessary to checkout the pull request if this run was triggered
+      # via an `issue_comment` action on a pull request.
+      - uses: actions/checkout@v3
+        if: github.event_name == 'issue_comment'
+        with:
+          ref: refs/pull/${{ github.event.issue.number }}/head
+          fetch-depth: 2
       - uses: actions/download-artifact@v3
         with:
           name: release-binary

.github/workflows/linux.yml

@@ -55,8 +55,16 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v3
+        if: github.event_name != 'issue_comment'
         with:
           fetch-depth: 2
+      # This is necessary to checkout the pull request if this run was triggered
+      # via an `issue_comment` action on a pull request.
+      - uses: actions/checkout@v3
+        if: github.event_name == 'issue_comment'
+        with:
+          ref: refs/pull/${{ github.event.issue.number }}/head
+          fetch-depth: 2
       - name: Run sccache-cache
         uses: mozilla-actions/sccache-action@v0.0.3
       - name: Select Python 3.9

.github/workflows/mac.yml

@@ -41,8 +41,16 @@ jobs:
     runs-on: macos-12
     steps:
       - uses: actions/checkout@v3
+        if: github.event_name != 'issue_comment'
         with:
           fetch-depth: 2
+      # This is necessary to checkout the pull request if this run was triggered
+      # via an `issue_comment` action on a pull request.
+      - uses: actions/checkout@v3
+        if: github.event_name == 'issue_comment'
+        with:
+          ref: refs/pull/${{ github.event.issue.number }}/head
+          fetch-depth: 2
       - name: Run sccache-cache
         uses: mozilla-actions/sccache-action@v0.0.3
       - name: Bootstrap
@@ -106,9 +114,17 @@ jobs:
   #     matrix:
   #       chunk_id: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
   #   steps:
-  #     - uses: actions/checkout@v3
+  #   - uses: actions/checkout@v3
-  #       with:
+  #     if: github.event_name != 'issue_comment'
-  #         fetch-depth: 2
+  #     with:
+  #       fetch-depth: 2
+  #   # This is necessary to checkout the pull request if this run was triggered
+  #   # via an `issue_comment` action on a pull request.
+  #   - uses: actions/checkout@v3
+  #     if: github.event_name == 'issue_comment'
+  #     with:
+  #       ref: refs/pull/${{ github.event.issue.number }}/head
+  #       fetch-depth: 2
   #     - uses: actions/download-artifact@v3
   #       with:
   #         name: release-binary-macos

.github/workflows/windows.yml

@@ -39,8 +39,16 @@ jobs:
     runs-on: windows-2019
     steps:
       - uses: actions/checkout@v3
+        if: github.event_name != 'issue_comment'
         with:
           fetch-depth: 2
+      # This is necessary to checkout the pull request if this run was triggered
+      # via an `issue_comment` action on a pull request.
+      - uses: actions/checkout@v3
+        if: github.event_name == 'issue_comment'
+        with:
+          ref: refs/pull/${{ github.event.issue.number }}/head
+          fetch-depth: 2
       - name: wix311-binaries
         shell: powershell
         run: |