Exclude cygrpc.so from the Python package
diff --git a/src/python/grpcio/precompiled.py b/src/python/grpcio/precompiled.py
index 05c651b..ae2a0c8 100644
--- a/src/python/grpcio/precompiled.py
+++ b/src/python/grpcio/precompiled.py
@@ -100,3 +100,5 @@
     sys.stderr.write(
         'could not write precompiled extension to directory: {} -> {}\n'
             .format(url, target_path))
+    return
+  setup_arguments['package_data']['grpc._cython'].append('cygrpc.so')