BUG #7783: lower & upper function incorrect work

The following bug has been logged on the website:

Bug reference:      7783
Logged by:          Alexander Shniperson
Email address:      alex.shniperson@gmail.com
PostgreSQL version: 9.1.7
Operating system:   osx lion 10.7.5
Description:        =


Hi.

I have problem at my project, try to do simple steps:
1) create DataBase with
ENCODING =3D 'UTF8'
LC_COLLATE =3D 'C'
LC_CTYPE =3D 'C'

2) create new table at just created database

CREATE TABLE testtable
(
  id serial NOT NULL,
  name character varying(50) NOT NULL,
  CONSTRAINT testtable_pkey PRIMARY KEY (id )
)

3) insert one simple record with Russian word

INSERT INTO testtable (id, name) VALUES (1, '=D0=97=D0=B0=D0=BB=D0=BE=D0=B3=
');

4) try to select data with upper & lower functions with 'like' operator =


select *, lower(name), upper(name) from testtable where lower(name) like
'%=D0=B7=D0=B0=D0=BB=D0=BE=D0=B3%'

5) as result you must see nothing, just fields without data

fix it please, thanks.