Fix erroneous attribute name.
This defect was introduced in 9e4d0610ea5e2bb302c. I had thought that
this code was exercised in tests but it is bypassed by the use of
grpc_test.beta.test_utilities.not_really_secure_channel. :-(
diff --git a/src/python/grpcio/grpc/beta/implementations.py b/src/python/grpcio/grpc/beta/implementations.py
index 9b461fb..c9d64ad 100644
--- a/src/python/grpcio/grpc/beta/implementations.py
+++ b/src/python/grpcio/grpc/beta/implementations.py
@@ -147,7 +147,7 @@
A secure Channel to the remote host through which RPCs may be conducted.
"""
intermediary_low_channel = _intermediary_low.Channel(
- '%s:%d' % (host, port), client_credentials.intermediary_low_credentials)
+ '%s:%d' % (host, port), client_credentials._intermediary_low_credentials)
return Channel(intermediary_low_channel._internal, intermediary_low_channel) # pylint: disable=protected-access