Mandatory list as attributes gives exception

[bartv]

entity Test:
    string[] bla
end

Test()

implement Test using std::none

produces

Traceback (most recent call last):
  File "/home/bart/.virtualenvs/inmanta/bin/inmanta", line 11, in <module>
    load_entry_point('inmanta', 'console_scripts', 'inmanta')()
  File "/home/bart/workspace/inmanta/src/inmanta/app.py", line 391, in app
    options.func(options)
  File "/home/bart/workspace/inmanta/src/inmanta/app.py", line 121, in compile_project
    result = do_compile()
  File "/home/bart/workspace/inmanta/src/inmanta/compiler.py", line 45, in do_compile
    success = sched.run(compiler, statements, blocks)
  File "/home/bart/workspace/inmanta/src/inmanta/execute/scheduler.py", line 309, in run
    self.freeze_all(excns)
  File "/home/bart/workspace/inmanta/src/inmanta/execute/scheduler.py", line 55, in freeze_all
    i.final(exns)
  File "/home/bart/workspace/inmanta/src/inmanta/execute/runtime.py", line 660, in final
    low = attr.low
AttributeError: 'Attribute' object has no attribute 'low'