job.frequency() throws Exception, when month or weekday are specified in string ranges

[Harun Prasad]

Calling Frequency function on a CronItem throws error when the month or day of the week are specified in string ranges like JAN-MAR or MON-FRI. Below is an example.

>>> from crontab import CronTab
>>> cron = CronTab()
>>> job = cron.new()
>>> job.setall('*/15 15 * * MON-FRI')
True
>>> job.frequency()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.6/site-packages/crontab.py", line 491, in frequency
    return self.frequency_per_year() * self.frequency_per_day()
  File "/usr/lib/python2.6/site-packages/crontab.py", line 501, in frequency_per_year
    weekdays = list(self[4])
  File "/usr/lib/python2.6/site-packages/crontab.py", line 733, in __iter__
    for bit in part.range():
  File "/usr/lib/python2.6/site-packages/crontab.py", line 861, in range
    return range(self.vfrom, self.vto+1, self.seq)
TypeError: unsupported operand type(s) for +: 'CronValue' and 'int'
>>>

Attached is the patch for this bug.

[Martin Owens (doctormo)]

I've committed r76 which contains a test which show the failure before the fix and that the fix works afterwords.