For 37 years, Emmerson Mnangagwa was Robert Mugabe’s right-hand man and one of his staunchest defenders. “Zanu-PF is a sacred party,” he told a crowd at a ZANU-PF rally earlier this year in central Zimbabwe. “It will rule and rule. Those barking will continue doing that while Zanu-PF remains in power. Forward with Mr Mugabe. Forward…