fix bugs of regression test (#5380)

* fix the the issue that `IS_PR `environment takes no effect

* fix the branch checkout

.github/workflows/performance-regression-test.yml

@@ -13,7 +13,15 @@ jobs:
     runs-on: [Rohan, ubuntu-20.04-lts]
     if: github.event.schedule || github.event.issue.pull_request && github.event.comment.body=='APRT'
     steps:
-      - uses: actions/checkout@v3
+      - name: checkout (schedule)
+        if: github.event.schedule
+        uses: actions/checkout@v3
+
+      - name: checkout (pr comments)
+        if: github.event.issue.pull_request
+        uses: actions/checkout@v3
+        with:
+          ref: ${{ format('refs/pull/{0}/merge', github.event.issue.number) }}
 
       - name: Set up Python 
         uses: actions/setup-python@v2
@@ -28,13 +36,9 @@ jobs:
           pip install twine
           pip install psycopg2-binary
 
-      - name: Check if it is triggered by PR comments
-        if: github.event.issue.pull_request
-        run: |
-          export IS_PR=1
-
       - name: Run benchmark
         run: |
           python python/nano/benchmark/run.py resnet50
         env: 
           ANALYTICS_ZOO_ROOT: ${{ github.workspace }}
+          IS_PR: ${{ github.event.issue.pull_request != null}}

python/nano/benchmark/run.py

@@ -50,7 +50,7 @@ def _extract_logs(output: str):
         return logs
 
     def _save_logs(self, logs: list):
-        is_pr = True if os.environ.get('IS_PR') is not None else False
+        is_pr = True if os.environ.get('IS_PR') == 'true' else False
         timestamp = datetime.now()
         conn = psycopg2.connect(
             database=self._get_secret('DB_NAME'),