Flag --incompatible_load_java_rules_from_bzl will break Bazel toolchains in Bazel 1.2.1

Incompatible flag --incompatible_load_java_rules_from_bzl will break Bazel toolchains once Bazel 1.2.1 is released.

Please see the following CI builds for more information:

* [RBE (:ubuntu: 16.04, OpenJDK 8)](RBE (:ubuntu: 16.04, OpenJDK 8))
* [RBE (:ubuntu: 16.04, OpenJDK 8)](RBE (:ubuntu: 16.04, OpenJDK 8))

Questions? Please file an issue in https://github.com/bazelbuild/continuous-integration

**Important**: Please do NOT modify the issue title since that might break our tools.

Start with the two linked Buildkite CI builds for the --incompatible_load_java_rules_from_bzl failure and inspect the Bazel toolchain configurations in this repository. Determine which configuration is affected and verify that the toolchains continue to work with Bazel 1.2.1; the issue provides no file or test name.

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