Add patch to protobuf

bazel/grpc_deps.bzl

@@ -175,6 +175,8 @@ def grpc_deps():
                 "https://storage.googleapis.com/grpc-bazel-mirror/github.com/google/protobuf/archive/19fb89416f3fdc2d6668f3738f444885575285bc.tar.gz",
                 "https://github.com/google/protobuf/archive/19fb89416f3fdc2d6668f3738f444885575285bc.tar.gz",
             ],
+            patches = ["//third_party:protobuf.patch"],
+            patch_args = ["-p1"],
         )
 
     if "com_google_googletest" not in native.existing_rules():

third_party/protobuf.patch

@@ -0,0 +1,14 @@
+diff --git a/python/google/protobuf/__init__.py b/python/google/protobuf/__init__.py
+index 97ac28028..8b7585d9d 100644
+--- a/python/google/protobuf/__init__.py
++++ b/python/google/protobuf/__init__.py
+@@ -31,3 +31,9 @@
+ # Copyright 2007 Google Inc. All Rights Reserved.
+
+ __version__ = '3.14.0'
++
++if __name__ != '__main__':
++  try:
++    __import__('pkg_resources').declare_namespace(__name__)
++  except ImportError:
++    __path__ = __import__('pkgutil').extend_path(__path__, __name__)