don't kill if pid same as file (#8997) (#8998)

The pid file needs to be deleted.

celery/platforms.py

@@ -188,6 +188,7 @@ def remove_if_stale(self):
             return True
         if pid == os.getpid():
             # this can be common in k8s pod with PID of 1 - don't kill
+            self.remove()
             return True
 
         try:

t/unit/utils/test_platforms.py

@@ -696,7 +696,7 @@ def test_remove_if_stale_same_pid(self):
         p.remove = Mock()
 
         assert p.remove_if_stale()
-        p.remove.assert_not_called()
+        p.remove.assert_called_with()
 
     @patch('os.fsync')
     @patch('os.getpid')