[f-spot] prevent crash on Timeline when PhotoQuery is empty

[Stephane Delcroix <sdelcroix src gnome org>]

commit 9968374c80ae5d974a95829420a9136c771a2fcb
Author: Mike Gemünde <mike gemuende de>
Date:   Mon Jul 13 09:19:03 2009 +0200

    prevent crash on Timeline when PhotoQuery is empty

 src/PhotoQuery.cs |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/src/PhotoQuery.cs b/src/PhotoQuery.cs
index 819b54f..ad2a67e 100644
--- a/src/PhotoQuery.cs
+++ b/src/PhotoQuery.cs
@@ -306,6 +306,9 @@ namespace FSpot {
 
 		private int LookupItem (System.DateTime date, bool asc)
 		{
+			if (Count == 0)
+				return -1;
+			
 			uint timer = Log.DebugTimerStart ();
 			int low = 0;
 			int high = Count - 1;