I still can't replicate the symptom, but I can confirm that the tasks being run don't see
Guessing it's because the code setting this is a context manager wrapping the definition of the function passed into multiprocessing -- not surprised that relying on global module state could cause hijinx like this.
What is odd is that the
Will experiment with explicitly handing a copy of
I'm committing this change to the 1.4 branch and merging it into master on the assumption that it does fix the problem. Attn @shaftoe & @dmcquay if either of you are up to testing from a Git checkout :)