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
I'm not suggesting anything. I'm just explaining why I though it may be there and why I though it maybe worth leaving.

Just delete the lines.