desc: Regression test for issue #619 "Python driver doesn't support inserting objects w/ 'self' as a key"

tests:

    - py: r.expr({"self":"foo"})
      ot: ({'self':'foo'})

    - py: r.expr(1).do(lambda x:{'self':x})
      ot: ({'self':1})

    - py: r.expr({"a":{"self":1}})
      ot: ({"a":{"self":1}})

    - py: r.expr({"self":{"self":{"self":1}}})
      ot: ({"self":{"self":{"self":1}}})