python-end-of-defun-function now works correctly when comments are not indented properly.

python-end-of-defun-function now works correctly when comments are not indented properly.

Calling `end-of-defun' on a python file will now do the correct thing,
even for cases like this:

    def fib(n):
        if n < 2:
    #       base cases
            return n
        else:
            return fib(n - 2) + fib(n - 1)