Attempt to run 2.23.9 convert-ly fails

[Kenneth Wolcott]

~/Downloads/lilypond-2.23.9/bin/convert-ly
../../lp_2.22.2/source/Twelve_Days_of_Christmas_arranged_for_Brass_Quintet.ly
> ./Twelve_Days_of_Christmas_arranged_for_Brass_Quintet.ly
Traceback (most recent call last):
  File "/Users/kwolcott/Downloads/lilypond-2.23.9/bin/../libexec/convert-ly",
line 82, in <module>
    import convertrules
ModuleNotFoundError: No module named 'convertrules'