1.1 --- a/imiptools/data.py Fri Sep 18 23:45:56 2015 +0200
1.2 +++ b/imiptools/data.py Sat Sep 19 00:11:13 2015 +0200
1.3 @@ -394,7 +394,7 @@
1.4 previous RDATE properties and ignoring any RRULE properties.
1.5 """
1.6
1.7 - old_values = set(self.get_date_values("RDATE"))
1.8 + old_values = set(self.get_date_values("RDATE") or [])
1.9 new_rdates = []
1.10
1.11 if self.has_key("RDATE"):
1.12 @@ -407,7 +407,7 @@
1.13 if new_rdates:
1.14 self["RDATE"] = new_rdates
1.15
1.16 - return old_values != set(self.get_date_values("RDATE"))
1.17 + return old_values != set(self.get_date_values("RDATE") or [])
1.18
1.19 def correct_object(self, tzid, permitted_values):
1.20