[CalendarServer-users] Sending iMIP messages with no icon-pngs fails, possible fix

[Markus Stürmer]

I think I found a small bug in
	twistedcaldav/mail.py

When providing no icons,
	1114         iconPath = self.getIconPath(details, canceled,  
language=language)
will set iconPath to "None" and
	1280         if os.path.exists(iconPath) and htmlTemplate.find("cid:% 
(iconName)s") != -1:
will fail with such an error message:
2009-04-17 14:23:27+0200 [-] [mailgateway] 	exceptions.TypeError:  
coercing to Unicode: need string or buffer, NoneType found

I catched that case by extending the test:
1280         if iconPath != None and os.path.exists(iconPath) and  
htmlTemplate.find("cid:%(iconName)s") != -1:

Regards,
Markus