The working example is running with

pants test packages/projA::

The broken example is

pants test packages/projB::

The only difference between those two is the entrypoint.

projA Build file:

entry_points = {
    "test":{"projA": "src.projA.conftest.run"},
},

Broken, but wanted entrypoint of projB:

entry_points = {
    "test":{"projB": "projB.conftest.run"},
},

Right now, this messes the entrypoint of the packages up.