Solved this myself by generating of a log by appending
2> /config/command.log
to my command line in the command_line sensor, which showed the command_line sensor did not find the py module (which was installed by terminal) then by looking at this post
and circumventing the issue of the py module not being available for the command sensor (not sure why this error occurs as on the terminal (which is run under rooot) the module was installed) but in any case, the sensor works.