> It isn't being careful when calling PyErr_SetFromErrno inside the
> Py_UniversalNewlineFread function since this function is being called
> all over fileobject after releasing the GIL.. so, isn't this just a
> matter of adding pairs of PyGILState_Ensure/PyGILState_Release around
> these calls to PyErr_SetFromErrno in this specific function ?

Perhaps that could fix this problem (or perhaps not - is
PyGILState_Ensure guaranteed to do the right thing, even in the
presence of multiple interpreters?)

My concern is that this patch may contain other bugs. I am apparently
incapable of reviewing it correctly, and nobody else has offered a
careful review.