Comment #23 on issue 1525 by smi...@gmail.com: No integration by substitution
http://code.google.com/p/sympy/issues/detail?id=1525

I got too quick on the trigger. This now breaks the tutorial example:

File "c:\users\leslie\sympy\doc\src\tutorial.txt", line 537, in tutorial.txt
Failed example:
    factorial(x).series(x, 0, 3)
Exception raised:
    Traceback (most recent call last):
      File "C:\Python27\lib\doctest.py", line 1254, in __run
        compileflags, 1) in test.globs
      File "<doctest tutorial.txt[95]>", line 1, in <module>
        factorial(x).series(x, 0, 3)
      File "C:\Users\leslie\sympy\sympy\core\expr.py", line 1344, in series
        s1 = self._eval_nseries(x, n=n, logx=None)
      File "C:\Users\leslie\sympy\sympy\core\function.py", line 363, in
_eval_nseries
        g = self.taylor_term(i, arg, g)
      File "C:\Users\leslie\sympy\sympy\core\function.py", line 519, in
taylor_term
        return cls(x).diff(x, n).subs(x, 0) * x**n / C.Factorial(n)
      File "C:\Users\leslie\sympy\sympy\core\basic.py", line 804, in subs
        return self._subs_old_new(old, new)
      File "C:\Users\leslie\sympy\sympy\core\cache.py", line 103, in wrapper
        func_cache_it_cache[k] = r = func(*args, **kw_args)
      File "C:\Users\leslie\sympy\sympy\core\basic.py", line 813, in
_subs_old_new
        return self._eval_subs(old, new)
      File "C:\Users\leslie\sympy\sympy\core\function.py", line 699, in
_eval_subs
        return Derivative(*map(lambda x: x._eval_subs(old, new), self.args))
      File "C:\Users\leslie\sympy\sympy\core\function.py", line 617, in
__new__
        raise ValueError('Derivative expects Symbol [, Integer] args but got
%s, %s' % (s, count))
    ValueError: Derivative expects Symbol [, Integer] args but got 0, 1

instead of

    >>> factorial(x).series(x, 0, 3)
                        2           2     2  2
                       x *EulerGamma    pi *x
    1 - x*EulerGamma + -------------- + ------ + O(x**3)
                             2            12

Do you know what to do, Aaron?

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