[evolution-data-server/wip/mcrha/libical-glib] Fix invalid unref of an ICalTimezone at e-cal-client.c:convert_to_tt_with_zone()

[Milan Crha <mcrha src gnome org>]

commit 5a8925f6cbc6ddb355a85bc058da4df38386ddd4
Author: Milan Crha <mcrha redhat com>
Date:   Wed Apr 17 14:39:34 2019 +0200

    Fix invalid unref of an ICalTimezone at e-cal-client.c:convert_to_tt_with_zone()

 src/calendar/libecal/e-cal-client.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)
---
diff --git a/src/calendar/libecal/e-cal-client.c b/src/calendar/libecal/e-cal-client.c
index 46f639f9c..61182a17a 100644
--- a/src/calendar/libecal/e-cal-client.c
+++ b/src/calendar/libecal/e-cal-client.c
@@ -2315,19 +2315,15 @@ convert_to_tt_with_zone (const ECalComponentDateTime *dt,
 
        if (i_cal_time_is_utc (value)) {
                zone = i_cal_timezone_get_utc_timezone ();
-               if (zone)
-                       g_object_ref (zone);
        } else if (tz_cb && !i_cal_time_is_date (value) && e_cal_component_datetime_get_tzid (dt)) {
                zone = (*tz_cb) (e_cal_component_datetime_get_tzid (dt), tz_cb_data, NULL, NULL);
        }
 
        if (!zone)
-               zone = default_timezone ? g_object_ref (default_timezone) : NULL;
+               zone = default_timezone;
 
        tt = i_cal_time_as_timet_with_zone (value, zone);
 
-       g_clear_object (&zone);
-
        return tt;
 }