DISTINCT and GROUP BY on a CLOB column was broken.

h2/src/main/org/h2/value/ValueLob.java

@@ -600,7 +600,11 @@ public class ValueLob extends Value {
                 return (int) (precision ^ (precision >>> 32));
             }
             try {
-                hash = ByteUtils.getByteArrayHash(getBytes());
+                if (type == CLOB) {
+                    hash = getString().hashCode();
+                } else {
+                    hash = ByteUtils.getByteArrayHash(getBytes());
+                }
             } catch (SQLException e) {
                 throw Message.convertToInternal(e);
             }

h2/src/test/org/h2/test/testSimple.in.txt

+create table test(t clob) as select 1;
+select distinct t from test;
+> 1;
+drop table test;
 create table test(id int unique not null);
 drop table test;
 create table test(id int not null unique);