transplant: widen wlock scope of transplant for consitency while processing Before this patch, "hg transplant" executes below before acquisition of wlock. - cmdutil.checkunfinished() - repo.status() for dirty check - repo.dirstate.parents() It may cause unintentional result, if another command runs parallelly (see also issue4368). This patch makes "hg transplant" acquire wlock before processing instead of acquiring wlock in each of 'transplanter.apply()' and 'transplanter.recover()'.