[shotwell] Add debug log when shifting events

[Jens Georg <jensgeorg src gnome org>]

commit 0046657c9f16706231be2194ed3d085ccb543c05
Author: Jens Georg <mail jensge org>
Date:   Wed Sep 21 20:56:07 2016 +0200

    Add debug log when shifting events
    
    This is to better be able to determine whether the event duplication reported
    in several bugs is happening due to event shifting
    
    Signed-off-by: Jens Georg <mail jensge org>

 src/Event.vala |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/src/Event.vala b/src/Event.vala
index 3518cab..084df97 100644
--- a/src/Event.vala
+++ b/src/Event.vala
@@ -617,8 +617,10 @@ public class Event : EventSource, ContainerSource, Proxyable, Indexable {
         
         // if the earliest's exposure time was on the day but *before* the boundary hour,
         // step it back a day to the prior day's boundary
-        if (earliest_tm.hour < EVENT_BOUNDARY_HOUR)
+        if (earliest_tm.hour < EVENT_BOUNDARY_HOUR) {
+            debug("Hour before boundary, shifting back one day");
             start_boundary -= TIME_T_DAY;
+        }
         
         time_t end_boundary = (start_boundary + TIME_T_DAY - 1);