On some system readline will fail to build as a module python, either because readline itself failed to build or because 5.1 is too recent for your system. In this case you can try to build w/o readline, for this:

1. cleanup your source dirs with a: "./clean_script all"
   
2. remove your target directory (or at least the readline .a and .so file in the lib dir)
3. edit pysrc/install_script and remove/comment out the lines about readline