turn tests with bazel head on (#214)

turn tests with bazel head on again:
Fixes https://github.com/bazelbuild/bazel-toolchains/issues/202
Issue was fixed with bazelbuild/bazel@6bc4528
diff --git a/.bazelci/presubmit.yml b/.bazelci/presubmit.yml
index 81bdb7c..623534b 100644
--- a/.bazelci/presubmit.yml
+++ b/.bazelci/presubmit.yml
@@ -3,8 +3,10 @@
   rbe_ubuntu1604:
     test_targets:
     - "//tests/config:debian-jessie-autoconfig_test"
+    - "//tests/config:debian-jessie-bazel-head-autoconfig_test"
     - "//tests/config:debian-jessie-custom-bazel-rc-version-autoconfig_test"
     - "//tests/config:ubuntu-xenial-autoconfig_test"
+    - "//tests/config:ubuntu-xenial-bazel-head-autoconfig_test"
     - "//tests/config:ubuntu-xenial-custom-bazel-rc-version-autoconfig_test"
     - "//tests/config:debian8_clang_autoconfig_test"
     - "//tests/config:external-repo-autoconfig_test"