In openerp It will first clean the leave intervals, to have an ordered list of not-overlapping intervals and initiate the current interval to be the base interval then before finishing skip the current interval and go to next beginning after the current interval: skip and get out of the loop because we are outside range. Use this code in your own module in .py file,

def remove_leaves(self, cr, uid, interval, leave_intervals, context=None):         
        if not interval:
            return interval
        if leave_intervals is None:
            leave_intervals = []
        intervals = []
        leave_intervals = self.interval_clean(leave_intervals)
        current_interval = [interval[0], interval[1]]
        for leave in leave_intervals:
            if leave[1] <= current_interval[0]:
                continue
            if leave[0] >= current_interval[1]:
                break
            if current_interval[0] < leave[0] < current_interval[1]:
                current_interval[1] = leave[0]
                intervals.append((current_interval[0], current_interval[1]))
                current_interval = [leave[1], interval[1]]
            # if current_interval[0] <= leave[1] <= current_interval[1]:
            if current_interval[0] <= leave[1]:
                current_interval[0] = leave[1]
        if current_interval and current_interval[0] < interval[1]:  
            intervals.append((current_interval[0], current_interval[1]))
        return intervals