I'll just chip this in, tell me what you think.
A lot of what we're seeing here - from the naive (IMO) belief that a set of demands that worked in the South African case can be transferred over to the Israeli/Palestinian case, without any acknowledgement of the fact that the differences between the two cases are as important as the parallels, to the idiotic "Hitler was a Zionist" shite, can be summed up as the work of people who don't want to think about the situation in a clear and detailed fashion. Well you do have to think about it.
As for Corbyn, I saw this on his twitter feed:
Good words, but they will have to be backed up with action. A party becomes strong by purging itself, as Lenin taught us.