[NTG-context] Negative width vrule ignored in LuaMETATeX

[SAO Ocean]

Hi,

As I'm beginning to use ConTeXt LMTX, I experimented with it a little and
noticed some of my old documents different. After some examination I found the
following example:

\starttext
a\vrule width -5pt height 0pt depth 0pt b
\stoptext

In LMTX, the result looks as if there is no `\vrule' between `a' and `b'. And if
I run with `context --engine=luatex', the expected result is back. I have
checked the luametatex manual but it doesn't seem to mention the difference. My
luametatex version is

mkiv lua stats  > used engine: luametatex version: 2.0502,
functionality level: 20200413, format id: 493, compiler: clang.

Is the behaviour expected? Or shall I use other method to get non-discardable
negative space?


Ao Shen