[evolution-exchange] Bug #621167 - NULL tzid passed in internal_get_timezone

[Milan Crha <mcrha src gnome org>]

commit e98cd5928dd147ac81f07446bfb2946daf8efccf
Author: Milan Crha <mcrha redhat com>
Date:   Fri Jun 25 13:48:39 2010 +0200

    Bug #621167 - NULL tzid passed in internal_get_timezone

 calendar/e-cal-backend-exchange.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/calendar/e-cal-backend-exchange.c b/calendar/e-cal-backend-exchange.c
index 93a5b16..77d641a 100644
--- a/calendar/e-cal-backend-exchange.c
+++ b/calendar/e-cal-backend-exchange.c
@@ -588,7 +588,7 @@ find_instance (ECalBackendExchange *cbex, ECalBackendExchangeComponent *ecomp, c
 		rtime = e2k_parse_timestamp (rid);
 		new_rid = icaltime_from_timet (rtime, FALSE);
 
-		f_zone = internal_get_timezone ((ECalBackend *) cbex, recur_id.datetime.tzid);
+		f_zone = (recur_id.datetime.tzid && *recur_id.datetime.tzid) ? internal_get_timezone ((ECalBackend *) cbex, recur_id.datetime.tzid) : icaltimezone_get_utc_timezone ();
 		recur_id.datetime.value->zone = f_zone;
 		inst_rid = icaltime_convert_to_zone (*recur_id.datetime.value, icaltimezone_get_utc_timezone ());