Fixed bugs pointed out by @jrjohansson.
Fixed bugs pointed out by @jrjohansson.

zasdfgbnm/qutip,zasdfgbnm/qutip,cgranade/qutip,anubhavvardhan/qutip,cgranade/qutip,qutip/qutip,anubhavvardhan/qutip,qutip/qutip