Issue #19638: Raise ValueError instead of crashing when converting billion character strings to float.

Change stacklevel in warnings.warn() for 'SO' key to 2.

with traceback_limit=1

Regression introduced by the implementation of the PEP 446 (non-inheritable
file descriptors by default).

master_fd must be set non-inheritable after the creation of the slave_fd,
otherwise grantpt(master_fd) fails with EPERM (errno 13).

name in their docstring. Patch written by Vajrasky Kok.