Found the problem. There were files missing in the directories "/usr/nsh/br/jython/bladelogic/cli" and "/usr/nsh/br/jython/bladelogic". Replacing the files fixed the problem listed above.
I'm having the same issue (exactly the same error) but on Windows. How did you find and replace the missing files?
I had another system with a working Jython installation. In an attempt to determine why one system had a working Jython environment, and the other did not, I noticed that there were a number of missing files.
What files are missing, and where can i get them from?
Well i fixed it by adding a folder called 'bladelogic' in the bin dir with the following inside.