Fix parallel testing (#254)
Fix parallel testing (#254)

* Fix parallel testing

We ran ctest . -j 10, and sometimes it happened that we got failing CI builds because the command in line 116 was executed in parallel.
```
[2020-04-28T19:13:39.193Z] 1: Traceback (most recent call last):
[2020-04-28T19:13:39.193Z] 1:   File "/opt/ros/eloquent/share/ament_cmake_test/cmake/run_test.py", line 23, in <module>
[2020-04-28T19:13:39.193Z] 1:     sys.exit(ament_cmake_test.main())
[2020-04-28T19:13:39.193Z] 1:   File "/opt/ros/eloquent/lib/python3.6/site-packages/ament_cmake_test/__init__.py", line 116, in main
[2020-04-28T19:13:39.193Z] 1:     os.makedirs(output_path)
[2020-04-28T19:13:39.193Z] 1:   File "/usr/lib/python3.6/os.py", line 220, in makedirs
[2020-04-28T19:13:39.193Z] 1:     mkdir(name, mode)
[2020-04-28T19:13:39.193Z] 1: FileExistsError: [Errno 17] File exists: 'some_dir/build/x86_debug/ros2/build_docker/functions/ament_cmake_gtest'
```

Signed-off-by: Florian Berchtold <ed5eb400d1c99eb56fb6ed6873c3389ce2c86f58@gmail.com>

* remove condition

Signed-off-by: blackliner <ed5eb400d1c99eb56fb6ed6873c3389ce2c86f58@gmail.com>
ament/ament_cmake,ament/ament_cmake,ament/ament_cmake