# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1508096063 -7200
# Node ID 22a0b7b99d8f1124edb1663ab426913fed59ddfc
# Parent  38ff4f58ae11240cee21f6afc869cfccd4cd0905
Preserve the main period in any expanded recurring period sequence.

diff -r 38ff4f58ae11 -r 22a0b7b99d8f imiptools/data.py
--- a/imiptools/data.py	Sun Oct 15 18:39:24 2017 +0200
+++ b/imiptools/data.py	Sun Oct 15 21:34:23 2017 +0200
@@ -1147,7 +1147,8 @@
         # must start from the first period, filtering from a start date must be
         # done after the instances have been obtained.
 
-        for recurrence_start in selector.materialise(dtstart, end, parameters.get("COUNT"), parameters.get("BYSETPOS"), inclusive):
+        for recurrence_start in selector.materialise(dtstart, end,
+            parameters.get("COUNT"), parameters.get("BYSETPOS"), inclusive):
 
             # Determine the resolution of the period.
 
@@ -1160,6 +1161,11 @@
 
             period = RecurringPeriod(recurrence_start, recurrence_end, tzid, "RRULE", dtstart_attr)
 
+            # Use the main period where it occurs.
+
+            if period == main_period:
+                period = main_period
+
             # Filter out periods before the start.
 
             if period.within(selection_period):