fix: wait for the stdout-filter thread in test_def_via_stdout_fails_session_action_on_error

The test asserted the parse-error log message immediately after
observing the session leave RUNNING, but the message is emitted by the
subprocess stdout-filter thread, which can still be draining the pipe
at that point. The race is intermittent on Windows CI (observed
repeatedly on python 3.9/3.14 windows-latest runners), where it fails
with the message absent from caplog and then passes on re-run. Poll
briefly for the message instead of racing the thread.

Signed-off-by: andychoquette <78888816+andychoquette@users.noreply.github.com>

Author: andychoquette

test/openjd/sessions_v0/test_session.py

@@ -3027,10 +3027,16 @@ def test_def_via_stdout_fails_session_action_on_error(
 
             # THEN
             assert session.state == SessionState.READY_ENDING
-            assert (
+            # The error is logged by the subprocess stdout-filter thread, which can
+            # still be draining the pipe when the state transition is observed above.
+            # Wait for the message rather than racing that thread.
+            expected_message = (
                 "openjd_env: FOO -- ERROR: Failed to parse environment variable assignment."
-                in caplog.messages
             )
+            deadline = time.monotonic() + 5
+            while expected_message not in caplog.messages and time.monotonic() < deadline:
+                time.sleep(0.1)
+            assert expected_message in caplog.messages
 
         callback.assert_has_calls(
             [