[libgee] Fix adding second element to priority queue, fixes bug #647162

[Maciej Marcin Piechotka <mpiechotka src gnome org>]

commit 5dfb5ee87a27f866910dc1081a956498e5239418
Author: Maciej Piechotka <uzytkownik2 gmail com>
Date:   Fri Apr 8 15:24:27 2011 +0200

    Fix adding second element to priority queue, fixes bug #647162

 gee/priorityqueue.vala       |    2 ++
 tests/testpriorityqueue.vala |   10 ++++++++++
 2 files changed, 12 insertions(+), 0 deletions(-)
---
diff --git a/gee/priorityqueue.vala b/gee/priorityqueue.vala
index fd45aac..0b6a93e 100644
--- a/gee/priorityqueue.vala
+++ b/gee/priorityqueue.vala
@@ -114,6 +114,8 @@ public class Gee.PriorityQueue<G> : Gee.AbstractQueue<G> {
 			_r_prime = new Type2Node<G> (element);
 			_r_prime.parent = _r;
 			_r.type2_child = _r_prime;
+			if (_compare (_r_prime, _r) < 0)
+				_swap_data (_r_prime, _r);
 		} else {
 			// Form a tree with a single node N of type I consisting of element e
 			Type1Node<G> node = new Type1Node<G> (element);
diff --git a/tests/testpriorityqueue.vala b/tests/testpriorityqueue.vala
index 9274dd8..676a814 100644
--- a/tests/testpriorityqueue.vala
+++ b/tests/testpriorityqueue.vala
@@ -89,5 +89,15 @@ public class PriorityQueueTests : QueueTests {
 		assert (test_queue.poll () == "twelve");
 		assert (test_queue.peek () == "two");
 		assert (test_queue.poll () == "two");
+
+		// Add decreasing elements
+		assert (test_queue.offer ("2"));
+		assert (test_queue.offer ("1"));
+
+		
+		assert (test_queue.peek () == "1");
+		assert (test_queue.poll () == "1");
+		assert (test_queue.peek () == "2");
+		assert (test_queue.poll () == "2");
 	}
 }