RuntimeError: File not found '_pyjs.js'
********** Building INFODIRECTORY **********
Building: InfoDirectory
PYJSPATH: ['/home/alessandror/.virtualenvs/brainaetic/build/pyjamas/examples/infohierarchy', '/home/alessandror/.virtualenvs/brainaetic/build/pyjamas/library', '/home/alessandror/.virtualenvs/brainaetic/build/pyjamas/addons']
Traceback (most recent call last):
  File "../../bin/pyjsbuild", line 21, in <module>
    pyjs.browser.build_script()
  File "/home/alessandror/.virtualenvs/brainaetic/build/pyjamas/pyjs/src/pyjs/browser.py", line 453, in build_script
    l()
  File "/home/alessandror/.virtualenvs/brainaetic/build/pyjamas/pyjs/src/pyjs/linker.py", line 113, in __call__
    self.visit_end_platform(platform)
  File "/home/alessandror/.virtualenvs/brainaetic/build/pyjamas/pyjs/src/pyjs/browser.py", line 85, in visit_end_platform
    self.app_files[platform] = self._generate_app_file(platform)
  File "/home/alessandror/.virtualenvs/brainaetic/build/pyjamas/pyjs/src/pyjs/browser.py", line 245, in _generate_app_file
    early_static_app_libs = static_code(early_static_app_libs)
  File "/home/alessandror/.virtualenvs/brainaetic/build/pyjamas/pyjs/src/pyjs/browser.py", line 174, in static_code
    raise RuntimeError('File not found %r' % lib)
RuntimeError: File not found '_pyjs.js'