FC_WEIGHT didn't match

[Bob Tennent]

Processing the following MWE

\documentclass{minimal}
\usepackage{mathpazo}
\begin{document}
foo
\end{document}

using a traditional latex -> dvips -> ps2pdf chain, I'm getting

DEBUG: FC_WEIGHT didn't match

from ps2pdf. This is on a linux system with the TL2019
pretest. I believe dvips is the culprit because I get the
same message on another system from the ps file, but not
vice versa.  I've not seen that error message before.
What does it mean?

Bob T.