I would like to take this opportunity to point out that everyone of us needs to be vigilant about this type of racism. One thing I recommend to my hiring managers is to not allow people from frictioned backgrounds to manage and interview people from the other side. Example problematic pairs for candidates/interviewers (not including the cast situation) include: Indians and Pakistanis, Serbians and Bosnians, Greeks and Turks, Chinese and Japanese.
One way I solve this is by introducing an independent observer/participant when situations like this emerge. This is costly but it has really worked to not only address this problem but also created an amazing diversity in my teams because it takes care of some of the implicit bias we all have to some degree.