This is only called on `prepareForDeletion` now, and since it's about to be deallocated (or at least it shouldn't be called anymore) the only thing that makes sense from this `reset` method is clearing the wp.com cookies. However, `clearWpcomCookies` doesn't care about usernames and clears every wp.com cookie.

This might break if you sign out of your main wp.com account and had a jetpack blog connected to a different account, although it would probably just authenticate again. Needs testing