in this case, i can't seen any point in providing pw_passwd
since no program that uses it (for anything non-trivial) could
work on Plan 9.   in fact, it's not even useful on unix systems:

	When  shadow(5)  passwords  are  enabled  (which  is  default  on  many
    GNU/Linux  installations)  the content of pw_passwd is usually not very
    useful. [because the contents are hidden in another file]

so: the program that refers to it won't be ported to plan 9,
and probably won't work on unix. best just to fix it by removing the reference.