# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1508883009 -7200
# Node ID 1aa3e8f9e5f17ae945dee91548bc1008b85ecd4b
# Parent  b35e8d4f7742759113d25866ef3cc5eab62c7992# Parent  f8b6e1ae40f429d568c2967b372942842971a5e9
Merged changes from the default branch.

diff -r b35e8d4f7742 -r 1aa3e8f9e5f1 imiptools/data.py
--- a/imiptools/data.py	Tue Oct 24 23:28:35 2017 +0200
+++ b/imiptools/data.py	Wed Oct 25 00:10:09 2017 +0200
@@ -1404,19 +1404,13 @@
 
     # Return a sorted list of the periods.
 
-    periods = list(MergingIterator([rule_periods, iter(rdates or [])]))
+    periods = MergingIterator([rule_periods, iter(rdates or [])])
 
     # Exclude exception dates.
 
-    exdates = obj.get_date_value_item_periods("EXDATE")
+    exdates = set(obj.get_date_value_item_periods("EXDATE", tzid) or [])
 
-    if exdates:
-        for period in exdates:
-            i = bisect_left(periods, period)
-            while i < len(periods) and periods[i] == period:
-                del periods[i]
-
-    return periods
+    return filter(lambda p, excluded=exdates: p not in excluded, periods)
 
 def get_main_period(periods):