'test_topic_pub_once' test flaky

[jacobperron]

Bug report

Required Info:

• Operating System:
  • Ubuntu 20.04 and macOS (Mojave)
• Installation type:
  • source
• Version or commit hash:
  • 95bfb05

Steps to reproduce issue

See failing CI jobs, for example:

• https://ci.ros2.org/job/nightly_linux_repeated/1925/testReport/ros2topic.ros2topic.test/test_cli/test_cli/
• https://ci.ros2.org/job/nightly_linux-aarch64_repeated/1248/testReport/ros2topic.ros2topic.test/test_cli/test_cli/
• https://ci.ros2.org/view/nightly/job/nightly_osx_repeated/2019/testReport/ros2topic.ros2topic.test/test_cli/test_cli/

Expected behavior

Tests pass

Actual behavior

Tests sometimes failing

Additional information

The tests are flaky; they do not occur every night. When they fail, it is not tied to one particular RMW implementation.

[cottsay]

This is back already, so clearly my change didn't fix it: http://build.ros2.org/job/Fci__nightly-debug_ubuntu_focal_amd64/170/testReport/junit/ros2topic.test/test_cli/test_cli/

[jacobperron]

I think this was actually fixed by the referenced PR (for master).

The Foxy CI failure should have been fixed the backport of this in #565.