Is there a comparison of what attitude self-identified Bernie supporters have towards Donald Trump compared to what attitude self-identified Hillary Clinton supporters have towards Donald Trump? Are supporters of one candidate more likely to report a favourable opinion of Trump than the other candidate?
As it happens FiveThirtyEight just posted an analysis of Sander's endorsement of Clinton, which includes a breakdown of poll results on a closely related question.
I haven't seen any polls which ask Sanders supporters about favorable/unfavorable status, but voting preferences make a good proxy.
The third parties in question are Gary Johnson and Jill Stein for two of the surveys. Stein was not an option in the Pew poll.