fixed sip_im_session to work with the latest eventlet

darcs-hash:20090113092614-b2873-3ce78339709e58081861c7329f221706a5f59f4e
Fixed broken error message on wrong Cython version

darcs-hash:20090113094413-58103-ffb43e9e164ea5606e2ee302df0d66cbe4719d7b