Bug: Catch any underlying exceptions from http.HTTPException

Resolves https://github.com/GoogleCloudPlatform/google-auth-library-
         python-httplib2/issues/6

Author: Poogles

google_auth_httplib2.py

@@ -21,7 +21,7 @@
 from google.auth import exceptions
 from google.auth import transport
 import httplib2
-
+import http
 
 _LOGGER = logging.getLogger(__name__)
 # Properties present in file-like streams / buffers.
@@ -194,8 +194,15 @@ def request(self, uri, method='GET', body=None, headers=None,
             body_stream_position = body.tell()
 
         # Make the request.
-        response, content = self.http.request(
-            uri, method, body=body, headers=request_headers, **kwargs)
+        try:
+            response, content = self.http.request(
+                uri, method, body=body, headers=request_headers, **kwargs)
+        # TODO: httplib2 should catch the lower http error, this is a bug and
+        # needs to be fixed there.  Catch the error for the meanwhile.
+        except (httplib2.HttpLib2Error, http.HTTPException) as exc:
+            _LOGGER.exception('Caught exception from http, reraising %r.',
+                              exc)
+            raise exceptions.TransportError(exc)
 
         # If the response indicated that the credentials needed to be
         # refreshed, then refresh the credentials and re-attempt the