[Zope] Plone Calendar not working with Zope 2.7.1

[Florian Schulze]

Hi!

I have just upgraded to Zope 2.7.1 and now the calendar isn't working  
anymore. It always shows January instead of the current month.

I couldn't find out which change in DateTime causes this problem.

Zope 2.7.1
Plone 2.0.3

Regards,
Florian Schulze