console: fix namespace problems when using slapos console with scripts

When using slapos console on scripts defining functions, for example

def my_request(*args, **kw):
  ...
  return request(*args, **kw)

the global names such as request where no longer available in the namespace of the function, because of a wrong usage of exec regarding locals/globals.

Co-authored-by: Kirill Smelkov kirr@nexedi.com