Merge branch 'stable-2.15' into stable-2.16 * stable-2.15: Upgrade bazlets to latest stable-2.15 to build with 2.15.18 API Bazel: Migrate workspace status script to python Upgrade bazlets to latest stable-2.15 Change-Id: I37427fb87cd43d001ee9b7d9022348e1cf1158b0