Introduce a Skyframe function: ActionEnvironmentFunction 

ActionEnvironmentFunction returns the list of environment
variable with the one overwritten by --action_env being
replaced. This let other Skyframe function declares
dependency to any value of the environment and being
influenced by the --action_env flag.

This will be used to declare dependency of remote repositories
on environment variables (step 3 of
https://bazel.build/designs/2016/10/18/repository-invalidation.html)

--
Change-Id: I1ed3fb6f48e8e17d4d64c903fccecb6ed7596350
Reviewed-on: https://cr.bazel.build/7974
PiperOrigin-RevId: 146918603
MOS_MIGRATED_REVID=146918603
diff --git a/src/test/java/com/google/devtools/build/lib/skyframe/TimestampBuilderTestCase.java b/src/test/java/com/google/devtools/build/lib/skyframe/TimestampBuilderTestCase.java
index 06c38e6..2eecace 100644
--- a/src/test/java/com/google/devtools/build/lib/skyframe/TimestampBuilderTestCase.java
+++ b/src/test/java/com/google/devtools/build/lib/skyframe/TimestampBuilderTestCase.java
@@ -211,6 +211,7 @@
             evaluationProgressReceiver);
     final SequentialBuildDriver driver = new SequentialBuildDriver(evaluator);
     PrecomputedValue.BUILD_ID.set(differencer, UUID.randomUUID());
+    PrecomputedValue.ACTION_ENV.set(differencer, ImmutableMap.<String, String>of());
     PrecomputedValue.PATH_PACKAGE_LOCATOR.set(differencer, pkgLocator.get());
 
     return new Builder() {