old_contents: import subprocess
  
  def test_execute():
      assert 0 == subprocess.call(['python', '-m', 'doit', 'list'])
  
  
new_contents: import sys
  import subprocess
  
  import pytest
  
  @pytest.mark.skipif('sys.version_info < (2,7,0)')
  def test_execute():
      assert 0 == subprocess.call(['python', '-m', 'doit', 'list'])
  
  
subject: fix test on py2.6. skip python -m test