return timestamp when truncating a date

h2/src/main/org/h2/expression/Function.java

@@ -1512,11 +1512,6 @@ public class Function extends Expression implements FunctionCall {
                     // '10:00:00 -> 00:00:00).
                     result = v1.subtract(v1);
 
-                } else if (v1 instanceof ValueDate) {
-
-                    // Case where we already have the date truncated to the day.
-                    result = v1;
-
                 } else if (v1 instanceof ValueTimestampTimeZone) {
 
                     // Create a new ValueTimestampTimeZone by only setting the

h2/src/test/org/h2/test/scripts/functions/timeanddate/date_trunc.sql

@@ -11,10 +11,10 @@ select DATE_TRUNC('DAY', time '15:14:13');
 >> 00:00:00
 
 select DATE_TRUNC('day', date '2015-05-29');
->> 2015-05-29
+>> 2015-05-29 00:00:00
 
 select DATE_TRUNC('DAY', date '2015-05-29');
->> 2015-05-29
+>> 2015-05-29 00:00:00
 
 select DATE_TRUNC('day', timestamp '2015-05-29 15:14:13');
 >> 2015-05-29 00:00:00