Comment 0 for bug 1291850

In some cases the whole purpose of exception handler is to reraise proper type of exception - for such cases there is often no need to log original exception being dropped as described here: https://bugs.launchpad.net/neutron/+bug/1288188

The proposal would be to add 'log_orig_exception' flag simular to 'reraise' to let user omit logging original exception. Example of usage:

        try:
            res = self._get_by_id(context, model, id)
        except exc.NoResultFound:
            with excutils.save_and_reraise_exception() as ctx:
                ctx.log_orig_exception = False
                if issubclass(model, Vip):
                    raise loadbalancer.VipNotFound(vip_id=id)
                elif issubclass(model, Pool):
                    raise loadbalancer.PoolNotFound(pool_id=id)
                elif issubclass(model, Member):
                    raise loadbalancer.MemberNotFound(member_id=id)
                elif issubclass(model, HealthMonitor):
                    raise loadbalancer.HealthMonitorNotFound(monitor_id=id)
                # if no match - log original exception
                ctx.log_orig_exception = True
        return r