I am not sure I follow.  In configure.ac I see one check for Python:

  AC_SUBST(ASDLGEN)
  AC_CHECK_PROGS(PYTHON, python$PACKAGE_VERSION python3 python, not-found)
  if test "$PYTHON" = not-found; then
      ASDLGEN="@echo python: $PYTHON! cannot run \$(srcdir)/Parser/asdl_c.py #"
  else
      ASDLGEN="$PYTHON"
  fi

and a couple of uses for it in Makefile.pre.in:

  $(AST_H): $(AST_ASDL) $(ASDLGEN_FILES)
  	  $(MKDIR_P) $(AST_H_DIR)
	  $(ASDLGEN) -h $(AST_H_DIR) $(AST_ASDL)

  $(AST_C): $(AST_H) $(AST_ASDL) $(ASDLGEN_FILES)
	  $(MKDIR_P) $(AST_C_DIR)
	  $(ASDLGEN) -c $(AST_C_DIR) $(AST_ASDL)

Are you suggesting that the variable name 'ASDLGEN" be renamed to something more general so that any scripts that need to be run *before* building the interpreter can use it?

I don't see any other AC_CHECK_PROGS checks for Python in configure.ac.

Apologies if I am being dense today :-)