Install John the Ripper Jumbo
I had more luck using the latest Jumbro version (1.8.0.6).

To retrieve and compile:

git clone https://github.com/magnumripper/JohnTheRipper jumbo
cd jumbo/src
./configure --enable-mpi


Note there is no need to edit the Makefile to enable the MPI any more - the above command will get everything ready for building.

make clean


Boom - everything now working.