UTESTs- The current version of protobuf in voltha has problem in expanding two messages.

This happens when voltha utests are executed.

FAIL: Failure: AssertionError (Extensions "voltha.yang_child_rule" and "voltha.yang_child_rule" both try to extend message type "google.protobuf.MessageOptions" with field number 7761774.)
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Traceback (most recent call last):
File "/var/lib/jenkins/jobs/voltha-gerrit/workspace/incubator/voltha/venv-linux/lib/python2.7/site-packages/nose/loader.py", line 418, in loadTestsFromName
addr.filename, addr.module)
File "/var/lib/jenkins/jobs/voltha-gerrit/workspace/incubator/voltha/venv-linux/lib/python2.7/site-packages/nose/importer.py", line 47, in importFromPath
return self.importFromDir(dir_path, fqname)
File "/var/lib/jenkins/jobs/voltha-gerrit/workspace/incubator/voltha/venv-linux/lib/python2.7/site-packages/nose/importer.py", line 94, in importFromDir
mod = load_module(part_fqname, fh, filename, desc)
File "/var/lib/jenkins/jobs/voltha-gerrit/workspace/incubator/voltha/tests/utests/voltha/core/test_logical_device_agent.py", line 7, in <module>
from voltha.core import logical_device_agent
File "/var/lib/jenkins/jobs/voltha-gerrit/workspace/incubator/voltha/voltha/core/logical_device_agent.py", line 27, in <module>
from voltha.core.device_graph import DeviceGraph
File "/var/lib/jenkins/jobs/voltha-gerrit/workspace/incubator/voltha/voltha/core/device_graph.py", line 19, in <module>
from voltha.core.flow_decomposer import RouteHop
File "/var/lib/jenkins/jobs/voltha-gerrit/workspace/incubator/voltha/voltha/core/flow_decomposer.py", line 27, in <module>
from voltha.protos import openflow_13_pb2 as ofp
File "/var/lib/jenkins/jobs/voltha-gerrit/workspace/incubator/voltha/voltha/protos/openflow_13_pb2.py", line 18, in <module>
import yang_options_pb2 as yang_options_pb2
File "/var/lib/jenkins/jobs/voltha-gerrit/workspace/incubator/voltha/voltha/protos/yang_options_pb2.py", line 187, in <module>
google_dot_protobuf_dot_descriptor__pb2.MessageOptions.RegisterExtension(yang_child_rule)
File "/var/lib/jenkins/jobs/voltha-gerrit/workspace/incubator/voltha/venv-linux/local/lib/python2.7/site-packages/google/protobuf/internal/python_message.py", line 766, in RegisterExtension
cls.DESCRIPTOR.full_name, extension_handle.number))
AssertionError: Extensions "voltha.yang_child_rule" and "voltha.yang_child_rule" both try to extend message type "google.protobuf.MessageOptions" with field number 7761774.