mktexpk is called at every compilation

[u-fischer]

\input luaotfload.sty
\font\test=bbm10
\test abc
\bye

shows at every compilation

[1{c:/texlive/2018/texmf-var/fonts/map/pdftex/updmap/pdftex.map}])
kpathsea: Running mktexpk --mfmode / --bdpi 600 --mag 1+0/600 --dpi 600 bbm10

The command name is C:\texlive\2018\bin\win32\mktexpk
C:/Users/XXXX/.texlive2018/texmf-var/fonts/pk/ljfour/public/bbm/bbm10.600pk exists.
<<c:/Users/XXXX/.texlive2018/texmf-var/fonts/pk/ljfour/public/bbm/bbm10.600pk>><
c:/texlive/2018/texmf-dist/fonts/type1/public/amsfonts/cm/cmr10.pfb>
Output written on test-utf8.pdf (1 page, 9170 bytes).

See https://mailman.ntg.nl/pipermail/dev-luatex/2018-November/006146.html