Fix for a bug in SHOW GRANTS when :

grant on database.* to xx@yy with grant option;

is done.

mysql-test/r/grant.result

@@ -64,3 +64,8 @@ GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, REFERENCES, INDEX, CREATE TE
 revoke all privileges on mysqltest.* from mysqltest_1@localhost;
 delete from mysql.user where user='mysqltest_1';
 flush privileges;
+grant usage on test.* to user@localhost with grant option;
+show grants for user@localhost;
+Grants for user@localhost
+GRANT USAGE ON *.* TO 'user'@'localhost'
+GRANT USAGE ON `test`.* TO 'user'@'localhost' WITH GRANT OPTION

mysql-test/t/grant.test

@@ -39,3 +39,6 @@ show grants for mysqltest_1@localhost;
 revoke all privileges on mysqltest.* from mysqltest_1@localhost;
 delete from mysql.user where user='mysqltest_1';
 flush privileges;
+grant usage on test.* to user@localhost with grant option;
+show grants for user@localhost;
+

sql/item.cc

@@ -505,7 +505,7 @@ bool Item::save_in_field(Field *field, bool no_conversions)
   {
     double nr=val();
     if (null_value)
-      return set_field_to_null(field);
+      return set_field_to_null_with_conversions(field, no_conversions);
     field->set_notnull();
     field->store(nr);
   }

sql/sql_acl.cc

@@ -2894,6 +2894,8 @@ int mysql_show_grants(THD *thd,LEX_USER *lex_user)
 
 	if (test_all_bits(want_access,(DB_ACLS & ~GRANT_ACL)))
 	  db.append("ALL PRIVILEGES",14);
+	else if (!(want_access & ~GRANT_ACL))
+	  db.append("USAGE",5);	
 	else
 	{
 	  int found=0, cnt;