Add a warning for internal checkouts.

Change-Id: Idf2786e80000c06e1012caff15ad0d91b517fdf0
diff --git a/setup.sh b/setup.sh
index bc3b4ff..61f8ae7 100755
--- a/setup.sh
+++ b/setup.sh
@@ -138,6 +138,13 @@
     fi
 fi
 
+if [[ "${ROOTDIR}/INTERNAL_NOTICE.md" ]]; then
+    echo
+    echo '*** WARNING: Your repo configuration includes closed-source internal'
+    echo '*** repositories. Please watch your step when you contribute code.'
+    echo
+fi
+
 echo ========================================
 echo ROOTDIR="${ROOTDIR}"
 echo OUT="${OUT}"