Fix location of external jars

com.google.devtools.bazel.e4b/resources/tools/must/be/unique/e4b_aspect.bzl

diff --git a/com.google.devtools.bazel.e4b/resources/tools/must/be/unique/e4b_aspect.bzl b/com.google.devtools.bazel.e4b/resources/tools/must/be/unique/e4b_aspect.bzl
index 84b23ea..4ff9685 100644
--- a/com.google.devtools.bazel.e4b/resources/tools/must/be/unique/e4b_aspect.bzl
+++ b/com.google.devtools.bazel.e4b/resources/tools/must/be/unique/e4b_aspect.bzl
@@ -24,9 +24,7 @@
     return struct(**d)
 
 def artifact_location(file):
-  if file == None:
-    return None
-  return ((file.root.path + "/") if not file.is_source else "") + file.short_path
+  return None if file == None else file.path
 
 def library_artifact(java_output):
   if java_output == None or java_output.class_jar == None: