Allow select the same source and destination calendar in Copy To Calendar

This way one can "duplicate" an event in the calendar. Move To Calendar
still requires the source and the destination calendars being different.

src/calendar/gui/comp-util.c

@@ -1088,6 +1088,7 @@ cal_comp_transfer_item_to_sync (ECalClient *src_client,
 	struct ForeachTzidData ftd;
 	ECalClientSourceType source_type;
 	GHashTable *processed_uids;
+	gboolean same_client;
 	gboolean success = FALSE;
 
 	g_return_val_if_fail (E_IS_CAL_CLIENT (src_client), FALSE);
@@ -1112,6 +1113,8 @@ cal_comp_transfer_item_to_sync (ECalClient *src_client,
 			g_return_val_if_reached (FALSE);
 	}
 
+	same_client = src_client == dest_client || e_source_equal (
+		e_client_get_source (E_CLIENT (src_client)), e_client_get_source (E_CLIENT (dest_client)));
 	processed_uids = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, NULL);
 
 	icalcomp_event = icalcomponent_get_first_component (icalcomp_vcal, icalcomp_kind);
@@ -1132,7 +1135,10 @@ cal_comp_transfer_item_to_sync (ECalClient *src_client,
 		if (g_hash_table_lookup (processed_uids, uid))
 			continue;
 
-		success = e_cal_client_get_object_sync (dest_client, uid, NULL, &icalcomp, cancellable, &local_error);
+		if (do_copy && same_client)
+			success = FALSE;
+		else
+			success = e_cal_client_get_object_sync (dest_client, uid, NULL, &icalcomp, cancellable, &local_error);
 		if (success) {
 			success = e_cal_client_modify_object_sync (
 				dest_client, icalcomp_event, E_CAL_OBJ_MOD_ALL, cancellable, error);

src/calendar/gui/e-cal-ops.c

@@ -2039,7 +2039,7 @@ e_cal_ops_transfer_components (EShellView *shell_view,
 		ESource *source = key;
 		GSList *icalcomps = value;
 
-		if (!e_source_equal (source, destination))
+		if (!is_move || !e_source_equal (source, destination))
 			nobjects += g_slist_length (icalcomps);
 	}
 
@@ -2086,7 +2086,7 @@ e_cal_ops_transfer_components (EShellView *shell_view,
 		ESource *source = key;
 		GSList *icalcomps = value;
 
-		if (!e_source_equal (source, destination)) {
+		if (!is_move || !e_source_equal (source, destination)) {
 			GSList *link;
 
 			icalcomps = g_slist_copy (icalcomps);

src/modules/calendar/e-cal-shell-view-actions.c

@@ -538,7 +538,7 @@ cal_shell_view_transfer_selected (ECalShellView *cal_shell_view,
 	selected = e_calendar_view_get_selected_events (calendar_view);
 	g_return_if_fail (selected != NULL);
 
-	if (selected->data) {
+	if (selected->data && is_move) {
 		ECalendarViewEvent *event = selected->data;
 
 		if (is_comp_data_valid (event) && event->comp_data->client)