[luatex] \lefthyphenmin = 0 or \righthyphenmin inhibits hyphenation

[Patrick Gundlach]

Hi all,

\lefthyphenmin0
\righthyphenmin0
\showhyphens{computer}
\bye

these settings (or one of them) inhibit hyphenation. Is that on purpose? 

This is LuaTeX, Version 1.12.0 (TeX Live 2020) 
 restricted system commands enabled.
(./test.tex
Underfull \hbox (badness 10000) in paragraph at lines 3--3
[] \tenrm computer
)
(see the transcript file for additional information)
warning  (pdf backend): no pages of output.
Transcript written on test.log.



Patrick