working hours timesheet entree incorrectly passes ID to _on_change_ methods when creating a new line

In HR / Working Hours when adding a new line for timesheet entree using the web client, the last ID of table hr_analytic_line is passed to the on_change_ methods of the object. Consequently code in on_change_ methods that depends on the IDS parameter to be empty when creating a new line doesn't execute correctly.

consider the code below from my inherited hr.analytic.timesheet

def on_change_task_id(self, cr, uid, ids, nTaskId, cName, nAccountId):
        # Get the values for the linked project: project code and description
        if not nTaskId:
            nTaskId = 0

        # Get stored task_id
        nTaskIdOld = 0
        context = {}
        oTimeSheetLine = self.pool.get('hr.analytic.d2e_timesheet').read(cr, uid, ids, ['task_id',], context)
        if len(oTimeSheetLine) > 0:
            tplTaskIdOld = oTimeSheetLine[0]["task_id"]
            if tplTaskIdOld :
                nTaskIdOld = tplTaskIdOld[0]

            if not nTaskIdOld :
                nTaskIdOld = 0

        # Update project fields if task_id has changed
        if nTaskId <> nTaskIdOld :

The last line incorrectly returns true because nTaskIdOld contains an incorrect value.