Description:
When the first character after a list ordinal has the same style as the list ordinal, the list ordinal's border box disappears.

It's hard to understand without seeing images. So please have a look at the screenshots here:
https://ask.libreoffice.org/t/strange-bug-in-libreoffice-writer-same-color-eats-borders/99735

Steps to Reproduce:
1. create a list
2. style the list so that the list ordinals have a border box
3. also assign a custom style to the list ordinal, e.g. bold + blue color
   (I don't know if step 3 is a requirement, but that's my test case, so I
    mention it to be safe)
4. now assign the same style to the adjacent text (including the first character after the ordinal - this is key, because if the first character does not have the same style, the bug does not occur)

Actual Results:
the list ordinal's border box disappears

Expected Results:
the list ordinal's border box should not disappear


Reproducible: Always


User Profile Reset: No

Additional Info:
Version: 7.6.4.1 (X86_64) / LibreOffice Community
Build ID: e19e193f88cd6c0525a17fb7a176ed8e6a3e2aa1
CPU threads: 1; OS: Windows 10.0 Build 16299; UI render: Skia/Raster; VCL: win
Locale: de-DE (de_DE); UI: en-US
Calc: threaded