From the man page for env:
The historic - option has been deprecated but is still supported in this implementation.
What does the "historic - option" do?
In particular, why does it change which version of python is run?
~:$ env python Python 2.6.5 Stackless 3.1b3 060516 (release26-maint, Mar 24 2010, 09:47:07)
~:$ env - python Python 2.5.1 (r251:54863, Feb 6 2009, 19:02:12)