Minus charset in scan doesn't work

Hi,

I am currently working on blacklisting whitespace char (0x0020) from Noto Color Emoji.

And I know it's possible because of this fixed bug#31969

But unluckily it doesn't work.

I created a testcase like the original bug reporter Akira TAGOH:

    <match target="scan">
            <test name="family">
                    <string>VL Gothic</string>
            </test>
            <edit name="charset" mode="assign">
                    <minus>
                            <name>charset</name>
                            <charset>
                                    <range>
                                        <int>0x0030</int>
                                        <int>0x00FF</int>
                                    </range>
                            </charset>
                    </minus>
            </edit>
    </match>

I should get result like this:

FcConfigSubstitute test scan any family Equal "VL Gothic"
Substitute match
    scan any family Equal "VL Gothic"
edit
    Edit charset Assign charset Minus charset
;

Append list before 
Append list after  
    0000: 00000000 ffffffff fffffffe 7fffffff 00000000 ffffffff ffffffff fff

fffff

But I can only find the first part. There is no 'Append list after' stuff at all. I doubt if it is applied.

And in the final match, I can still view lots of chars that should be substracted:

FcConfigSubstitute editPattern has 42 elts (size 48)
    family: "VL Gothic"(s) "VL ゴシック"(s)
    ...
    charset:
    ...
      0030: ffffffff 38ff0001 fffffffe ffffffff fe7fffff ffffffff ffffffff ffffffff
      0031: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 ffff0000
      0032: 00000000 ffffffff fffe000f 00000000 ffffffff ffffffff ffffffff 7fffffff
      0033: ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff ffffffff 7fffffff
      0047: 80001000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
    ...

It doesn't seem to work at all.

Am I missing something? or this feature has been removed from fontconfig?

I think something introduced in 2010.12 should work after so many years...

Greetings

Marguerite