Restore error messages during a repository rule fetch failure to not suppress contextual console output

See https://github.com/bazelbuild/bazel/issues/6670#issuecomment-500037775

Closes #8584.

Change-Id: I5d69d73ac41d71c4ee75351aa52a7c5e3bccd6b4
PiperOrigin-RevId: 253645460
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeDependencyResolver.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeDependencyResolver.java
index e67fbb5..f8fd2e2 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeDependencyResolver.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeDependencyResolver.java
@@ -143,7 +143,8 @@
                   Event.error(
                       TargetUtils.getLocationMaybe(fromTarget),
                       String.format(
-                          "%s depends on %s in repository %s which failed to fetch",
+                          "%s depends on %s in repository %s which failed to fetch. "
+                              + e.getMessage(),
                           fromTarget.getLabel(),
                           label,
                           label.getPackageIdentifier().getRepository())));