System.StringException thrown when aborting a job in a rest controller

Welcome to the world of known issues :

https://success.salesforce.com/issues_view?id=a1p30000000SyhIAAS

As rao said, there is a SF known issue preventing jobs from being aborted in a custom rest controller.

Here is a simplified version of my job's execute method:

    public void execute(SchedulableContext SC) {
        //configUtil.getState() retrieves the custom setting with the 'RUNNING'/'STOPPED' state information.
        if(configUtil.getState() != 'RUNNING'){
            //abort the current job, and return.
            System.abortJob( SC.getTriggerId() );
            return;
        }

        //do stuff
        coolMethodThatDoesCoolStuff();

        //reschedule job to run again in 1 minute
        Datetime sysTime = System.now().addSeconds(60);      
        String chronExpression = '' + sysTime.second() + ' ' + sysTime.minute() + ' ' + sysTime.hour() + ' ' + sysTime.day() + ' ' + sysTime.month() + ' ? ' + sysTime.year();
        System.schedule( 'AmbitionPusherSelfSchedule' + sysTime, chronExpression, new Pusher() );
        //abort the current job instead of running again in an hour.
        System.abortJob( SC.getTriggerId() );
    }

and here is the code from the controller:

@HttpDelete
global static String stop(){
    configUtil.setState('STOPPED');
    return 'job stop requested';
}