please try the following
1) cd $NWCHEM_TOP/src
2) make nwchem_config NWCHEM_MODULES="all python"
3) cd python; make clean;make
4) cd ..
5) make PYTHONLIBRARY=so link
If this still does not work, please post the output of the command
grep -i python_input $NWCHEM_TOP/src/stubs.F