Allow BazelPackageLoader to load external repositories.
Also, disallow BazelPackageLoader from fetching missing external repos.

Integration tests for BazelPackageLoader wrt external repos will be left for a follow-up CL.

RELNOTES: None.
PiperOrigin-RevId: 188967694
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ClientEnvironmentFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/ClientEnvironmentFunction.java
index 7c4c798..37f111f 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/ClientEnvironmentFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ClientEnvironmentFunction.java
@@ -55,7 +55,7 @@
 
   private final AtomicReference<Map<String, String>> clientEnv;
 
-  ClientEnvironmentFunction(AtomicReference<Map<String, String>> clientEnv) {
+  public ClientEnvironmentFunction(AtomicReference<Map<String, String>> clientEnv) {
     this.clientEnv = clientEnv;
   }