python-shell-process-environment

python-shell-process-environment is a variable defined in `python.el'.
Its value is

nil

• This variable is safe as a file local variable if its value
  satisfies the predicate `listp'.

Documentation:
List of environment variables for Python shell.
This variable follows the same rules as `process-environment'
since it merges with it before the process creation routines are
called. When this variable is nil, the Python shell is run with
the default `process-environment'.

You can customize this variable.