Get rid of some unnecessary commented out code (issue #6849)

There is a lot of false positives (see [attached logs](http://code.google.com/p/sympy/issues/detail?id=3750#c1)), so I don't think that we should automate such cleanup.

fixes #6849
Now it fails with a type error (too few args), no idea how to fix this.

This assert was reverted back due to @asmeurer suggestion (see commits history).