Chicken-egg problem: USE_PYTHON after `.include <bsd.port.pre.mk>'

[Lev Serebryakov]

Hello, ports! How are you?

  I need add to port USE_PYTHON=yes, but only if user define
  WITH_PYTHON. I want to support Makefile.local, so, I need to put all
  WITH_* processing after `.include <bsd.port.pre.mk>' line. But
  USE_PYTHON should go BEFORE this line, otherwise bsd.python.mk will
  not be included!

  How this problem could be solved? Is it safe to include
  bsd.python.mk directly?

--
               Lev Serebryakov