With setuptools, when do __init__.py namespace packages disappear?

Question

The setuptools documentation details how to add code to files __init__.pyfrom namespaces:

You should not include any other code and data in the namespace package __init__.py. Despite the fact that it can work during development or when projects are installed as .egg files, it will not work when projects are installed using "system" packaging tools - in such cases the files __init__.pywill not be installed, not to mention completed .

However, I do not understand what "system" packaging tools are. Who are they? How can I reproduce this situation when the files __init__.pydisappeared?

Answer 1

@ Anzel's comment looked like a good answer, and I would say PEP-420 confirms this. In the Justification section, we read:

(, , sys.path). , __init__.py, . , Linux ( ) .. , - , . , __init__.py , , .

, __init__.py, ( ) .