Since it was announced last month that Pakistan’s army chief, Gen. Ashfaq Parvez Kayani, would be retiring, Prime Minister Nawaz Sharif has kept the country dangling on his choice, creating a new parlor game for the chattering classes in the process. General Kayani has been characteristically mum, except for an unusual press release that said he was leaving the office on Nov. 29, without closing out other options, even as he accepted the concurrent role of chairman of the Joint Chiefs of Staff....