adding target/test-classes only if testonly

scala/scala.bzl

@@ -311,8 +311,11 @@ def _write_launcher(ctx, rjars, main_class, jvm_flags, args="", wrapper_preamble
     runfiles_root = "${TEST_SRCDIR}/%s" % ctx.workspace_name
     # RUNPATH is defined here:
     # https://github.com/bazelbuild/bazel/blob/0.4.5/src/main/java/com/google/devtools/build/lib/bazel/rules/java/java_stub_template.txt#L227
-    classpath2 = ":".join(["%s" % (j.short_path) for j in rjars])
-    classpath = "target/test-classes:%s" % classpath2
+    classpath = ":".join(["${RUNPATH}%s" % (j.short_path) for j in rjars])
+
+    if ctx.attr.testonly:
+      classpath = ":".join(["%s" % (j.short_path) for j in rjars])
+      classpath = "target/test-classes:%s" % classpath
 
     jvm_flags = " ".join([ctx.expand_location(f, ctx.attr.data) for f in jvm_flags])
     javabin = "%s/%s" % (runfiles_root, ctx.executable._java.short_path)