fix for build 

Traceback (most recent call last):
  File "build/tools/roomservice.py", line 233, in <module>
    fetch_dependencies(repo_path)
  File "build/tools/roomservice.py", line 207, in fetch_dependencies
    dependencies = json.loads(dependencies_file.read())
  File "/usr/lib/python2.7/json/__init__.py", line 338, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python2.7/json/decoder.py", line 365, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python2.7/json/decoder.py", line 383, in raw_decode
    raise ValueError("No JSON object could be decoded")
ValueError: No JSON object could be decode