new_contents: from infiniteworld import SessionLockLost, MCInfdevOldLevel
  from templevel import TempLevel
  import unittest
  
  class SessionLockTest(unittest.TestCase):
      def test_session_lock(self):
          temp = TempLevel("AnvilWorld")
          level = temp.level
          level2 = MCInfdevOldLevel(level.filename)
          def touch():
              level.saveInPlace()
          self.assertRaises(SessionLockLost, touch)
  
  
subject: Add quick test for session locks.