Custom csv DictReader, as an iterator, that trunck "too long" lines

gistfile1.txt

def custom_dict_reader(csv_filename, delimiter="\t"):
    with open(csv_filename) as csv_file:
        header = list(map(str.strip, csv_file.readline().split(delimiter)))
        line_num = 2
        for line in csv_file.readlines():
            splitted = list(map(str.strip, line.split(delimiter)))
            if len(splitted) != len(header):
                print("WARNING: the number of rows in line ({}) doesn't match the number of elements in header ({}) ! Row will be truncated".format(
                    len(splitted), len(header)
                ))  
            values_dict = OrderedDict(zip(header, splitted))
            yield values_dict
            line_num += 1