From d2cf1ab0e27b3d794b28170fe745c84723209b86 Mon Sep 17 00:00:00 2001
From: Tim Peters <tim.peters@gmail.com>
Date: Fri, 2 Aug 2002 19:41:54 +0000
Subject: check_invariant():  Use the same child->parent "formula" used by
 heapq.py.

---
 Lib/test/test_heapq.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Lib/test/test_heapq.py b/Lib/test/test_heapq.py
index 016fd3a..879899e 100644
--- a/Lib/test/test_heapq.py
+++ b/Lib/test/test_heapq.py
@@ -8,8 +8,8 @@ import random
 def check_invariant(heap):
     # Check the heap invariant.
     for pos, item in enumerate(heap):
-        parentpos = ((pos+1) >> 1) - 1
-        if parentpos >= 0:
+        if pos: # pos 0 has no parent
+            parentpos = (pos-1) >> 1
             verify(heap[parentpos] <= item)
 
 def test_main():
-- 
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