[gnome-settings-daemon] color: Fix 'night shift'-style natural light settings

[Richard Hughes <rhughes src gnome org>]

commit 296560cf93c339466db1eeede6ce21a296166618
Author: Richard Hughes <richard hughsie com>
Date:   Wed Feb 8 15:52:10 2017 +0000

    color: Fix 'night shift'-style natural light settings

 plugins/color/gcm-self-test.c            |    3 +++
 plugins/color/gsd-natural-light-common.c |    6 +++++-
 2 files changed, 8 insertions(+), 1 deletions(-)
---
diff --git a/plugins/color/gcm-self-test.c b/plugins/color/gcm-self-test.c
index 08241ce..a5163a7 100644
--- a/plugins/color/gcm-self-test.c
+++ b/plugins/color/gcm-self-test.c
@@ -123,6 +123,9 @@ gcm_test_frac_day (void)
         /* test rollover to next day */
         g_assert (gsd_natural_light_frac_day_is_between (23, 20, 6));
         g_assert (!gsd_natural_light_frac_day_is_between (12, 20, 6));
+
+        /* test rollover to the previous day */
+        g_assert (gsd_natural_light_frac_day_is_between (5, 16, 8));
 }
 
 int
diff --git a/plugins/color/gsd-natural-light-common.c b/plugins/color/gsd-natural-light-common.c
index 10b693d..9150de6 100644
--- a/plugins/color/gsd-natural-light-common.c
+++ b/plugins/color/gsd-natural-light-common.c
@@ -121,6 +121,10 @@ gsd_natural_light_frac_day_is_between (gdouble value, gdouble start, gdouble end
         if (end < start)
                 end += 24;
 
+        /* wraparound to the previous day */
+        if (value < start && value < end)
+                value += 24;
+
         /* test limits */
-        return value > start && value < end;
+        return value > start && value <= end;
 }