Report Python version in the debuggee.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=187896037

Author: xinghuadou-google

src/googleclouddebugger/gcp_hub_client.py

@@ -467,13 +467,14 @@ def _QueryGcpProject(self, resource):
 
   def _GetDebuggee(self):
     """Builds the debuggee structure."""
-    major_version = version.__version__.split('.')[0]
+    major_version = 'v' + version.__version__.split('.')[0]
+    python_version = 'python36-gcp' if six.PY3 else 'python27-gcp'
 
     debuggee = {
         'project': self._project_number(),
         'description': self._GetDebuggeeDescription(),
         'labels': self._debuggee_labels,
-        'agentVersion': 'google.com/python27-gcp/v' + major_version
+        'agentVersion': 'google.com/%s/%s' % (python_version, major_version)
     }
 
     source_context = self._ReadAppJsonFile('source-context.json')

src/setup.py

@@ -113,6 +113,7 @@ def ReadConfig(section, value, default):
     keywords='google cloud debugger',
     classifiers=[
         'Programming Language :: Python :: 2.7',
+        'Programming Language :: Python :: 3.6',
         'Development Status :: 3 - Alpha',
         'Intended Audience :: Developers'
     ])