The find invocation used by the bin/tests/system/get_ports.sh script
("find . -maxdepth 1 -mindepth 1 -type d") assumes the list of
directories in bin/tests/system/ remains unchanged throughout the run
time of a single system test suite. With pytest in use and the
conftest.py file now present in bin/tests/system/, that assumption is no
longer true as a __pycache__ directory may be created when the first
pytest-based test is started. Since the list of names returned by the
above find invocation serves as a fixed-size array of "port range
slots", any changes to that list during a system test suite run may lead
to port assignment collisions [1].
Fix by making the find invocation more nuanced, so that it only returns
names of directories containing test code. Squash a grep / cut pipeline
into a single awk invocation.
[1] see commit 31e5ca4bd9
(cherry picked from commit 4e0d576858)