Yeah, I think the old tests are wrong. That came from issue 2571 (https://code.google.com/p/sympy/issues/detail?id=2571), but I think using `.subs` this way for indefinite integral is confusing. I think either `.replace` or `.xreplace` should be used for this functionality rather than `.subs`. There is also issue 3829 (https://code.google.com/p/sympy/issues/detail?id=3829), which seems to contradict these tests. What do these substitutions give you in your branch?