Issue#458 Missed some testScript.sql test cases, added two more

h2/src/test/org/h2/test/testScript.sql

@@ -9909,15 +9909,29 @@ select dateadd('year', -1, timestamp '2000-02-29 10:20:30.012345678') d1 from te
 > 1999-02-28 10:20:30.012345678
 > rows: 1
 
+-- Only 2 months difference, not a whole year
 select datediff('yy', timestamp '2003-12-01 10:20:30.0', timestamp '2004-01-01 10:00:00.0') d1 from test;
 > D1
 > --
+> 0
+> rows: 1
+
+select datediff('yy', timestamp '2003-12-01 10:20:30.0', timestamp '2004-12-01 10:20:30.0') d1 from test;
+> D1
+> --
 > 1
 > rows: 1
 
+-- Only 2 months difference, not a whole year
 select datediff('year', timestamp '2003-12-01 10:20:30.0', timestamp '2004-01-01 10:00:00.0') d1 from test;
 > D1
 > --
+> 0
+> rows: 1
+
+select datediff('year', timestamp '2003-12-01 10:20:30.0', timestamp '2004-12-01 10:20:30.0') d1 from test;
+> D1
+> --
 > 1
 > rows: 1