Python 3.14 appears to be broken

The simplified profile mode, which uses class variables to store the inheritance, seems not to work with python3.14:
class variables are not sent to the child processes, therefore each child gets an empty inheritance dictionary only. While this is expected 3.14 behaviour, it breaks (parallel) Fab builds atm.

Note that this seems to be unrelated to #581 (since the change that triggers the failure was only added a few weeks ago, while this ticket is much older)

Start by reproducing a parallel Fab build with Python 3.14 in simplified profile mode, then trace how the inheritance dictionary reaches child processes. The fix is complete when child processes receive the inherited profile data and parallel builds work under Python 3.14.

Written by the indexing model from the issue text.