Password requested when building VYOS 1.5 using Docker

Hello all. I am attempting to build the VYOS 1.5 ISO image using the docker container method and it is requesting for a password which is then followed by the error 'chsh: PAM: Authentication failure'
This occurs twice in the build process.
I have tried default password that is specified for a new install but no joy.
Any ideas on how to go around this or what the actual password is?