find the early initialization bug that makes keeping internal pytest_namespace necessary

[RonnyPfannschmidt]

in #2315 i had to commit afb1778
in order to keep pytest-xdist working correctly

this clearly indicates a bug in early initialization, and i'd like to rectify it
as its a requirement for deprecating pytest_namespace altogether

[nicoddemus]

@RonnyPfannschmidt I remember you tackling this, has this been fixed already perhaps?

[RonnyPfannschmidt]

Still not tackled, config is a utter mess

[RonnyPfannschmidt]

superseeded by my work on #3080 in #3376