Encountered error: 400 during build

[louwersj]

Encountered error: 400 Client Error: Bad Request ("Dockerfile parse error line 8: unknown instruction: ---")
Traceback (most recent call last):
File "/stage/builder/runner.py", line 290, in _run
self.build()
File "/stage/builder/runner.py", line 214, in build
self._build()
File "/stage/builder/runner.py", line 202, in _build
cache_repo)
File "/stage/builder/build.py", line 43, in build_image
for line in stream:
File "/usr/local/lib/python2.7/dist-packages/docker/api/client.py", line 305, in _stream_helper
yield self._result(response, json=decode)
File "/usr/local/lib/python2.7/dist-packages/docker/api/client.py", line 220, in _result
self._raise_for_status(response)
File "/usr/local/lib/python2.7/dist-packages/docker/api/client.py", line 216, in _raise_for_status
raise create_api_error_from_http_exception(e)
File "/usr/local/lib/python2.7/dist-packages/docker/errors.py", line 30, in create_api_error_from_http_exception
raise cls(e, response=response, explanation=explanation)
APIError: 400 Client Error: Bad Request ("Dockerfile parse error line 8: unknown instruction: ---")