test(jailer): do not kill screen with new_pid_ns

In our setup, if Firecracker is run by the screen
with --new-pid-ns passed to the jailer,
the Firecracker process detaches from the screen
causing the screen process to exit as well.
We attempt to kill the screen process by pid,
which causes a race condition.

This change lets the screen terminate on its own
without attempting to kill it.

Signed-off-by: Nikita Kalyazin <[email protected]>

Author: kalyazin

tests/framework/microvm.py

@@ -632,6 +632,12 @@ def spawn(
             )
             self._screen_pid = screen_pid
 
+        # If `--new-pid-ns` is used, the Firecracker process will detach from
+        # the screen and the screen process will exit. We do not want to
+        # attempt to kill it in that case to avoid a race condition.
+        if self.jailer.new_pid_ns:
+            self._screen_pid = None
+
         self._spawned = True
 
         if emit_metrics: