case sensitive grep broken with UTF8 in intrepid, breaking scripts

Binary package hint: grep

grep is badly broken with UTF8 in intrepid.

Intrepid:

$ echo FOOBAR | grep FOO
FOOBAR
$ echo FOOBAR | grep -i FOO
$ echo FOOBAR | grep -i foo
$

the expected behavior is like on Hardy:

$ echo FOOBAR | grep FOO
FOOBAR
$ echo FOOBAR | grep -i FOO
FOOBAR
$ echo FOOBAR | grep -i foo
FOOBAR
$

In both cases, my locale is set to en_US.UTF-8.

Looking at the package, there's debian/patches/66-match_icase.patch showing this:

>>>
This fixes
    echo Y | LC_ALL=en_US.UTF-8 grep -i '[y]'
The expected output is:
    Y

Without this patch, it works on non UTF-8 environment, but fails on UTF-8
environment.

The definition of RE_ICASE comes from the glibc (/usr/include/regex.h)

Maybe lib/posix/regex.h should be removed to enforce the usage of the
glibc's regex.h
<<<

$ echo Y | LC_ALL=en_US.UTF-8 grep -i '[y]'
$ echo Y | LC_ALL=C grep -i '[y]'
Y

So it seems it's indeed an UTF8 issue and that the patch is no longer sufficient.