[python-sybase] Small patch: factor out Cursor._checkready()

[Greg W. <gwa...@py...>]

Here's a small patch that I posted a few weeks ago.  I think it got lost
in the shuffle, since I never saw a response to my post.  It's a pure
refactoring: should have absolutely no effect on behaviour.  I've been
using it on my test server for several weeks now and it seems fine.

Andrew or Dave, can you give thumbs up or thumbs down on this one?

        Greg