\capitalgrave doesn't give accent in tabbing when used with lualatex

[u-fischer]

Minimal example showing the bug

\RequirePackage{latexbug}  
\documentclass{article}
\begin{document}
\begin{tabbing}
 \capitalacute a \capitalgrave a  \capitalmacron a 
\end{tabbing}  
\end{document}

this gives accents with pdflatex

but tabbing commands with lualatex:

Log file (required) and possibly PDF file

test-utf8.log

[FrankMittelbach]

yeah, guess

\makeatletter
  \def\capitalacute{\@tabacckludge'}
  \def\capitalgrave{\@tabacckludge`}
  \def\capitalmacron{\@tabacckludge=}
\makeatother

is needed as the default definition

[FrankMittelbach]

Went out with LaTeX 2020-02-02 PL 2