Precision for UPPER function is wrong if the returned value is longer than the literal argument

Seen in ij in a database with territory based collation and German locale:

==vv= COPIED FROM IJ CONSOLE =vv==
ij> VALUES UCASE('Straßenbahn');
1
-----------
STRASSENBA&

1 Zeile ausgewählt
==================================

And with JDBC calls:

Connection c = DriverManager.getConnection(
"jdbc:derby:memory:db;create=true;territory=de_DE;" +
"collation=TERRITORY_BASED");
Statement s = c.createStatement();
ResultSet rs = s.executeQuery("values upper('Straße')");
System.out.println(rs.getMetaData().getPrecision(1));
rs.next();
System.out.println(rs.getString(1));

This prints

6
STRASSE

The precision is wrong, since the returned value is 7 characters long.