Bump master version numbers
diff --git a/src/python/grpcio/grpc_version.py b/src/python/grpcio/grpc_version.py
index ea38526..c197e92 100644
--- a/src/python/grpcio/grpc_version.py
+++ b/src/python/grpcio/grpc_version.py
@@ -29,4 +29,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio/grpc_version.py.template`!!!
 
-VERSION='1.1.0.dev0'
+VERSION='1.2.0.dev0'