diff --git a/build-support/docker/travis_ci_py27_ucs2/Dockerfile b/build-support/docker/travis_ci_py27_ucs2/Dockerfile
index 35e09f50534..2bc7fd29410 100644
--- a/build-support/docker/travis_ci_py27_ucs2/Dockerfile
+++ b/build-support/docker/travis_ci_py27_ucs2/Dockerfile
@@ -1,6 +1,9 @@
-# Copyright 2017 Pants project contributors (see CONTRIBUTORS.md).
+# Copyright 2019 Pants project contributors (see CONTRIBUTORS.md).
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 
+# This file duplicates travis_ci/Dockerfile, except it installs Python 2.7 instaed of Python 3.6
+# and adds the env var PYTHON_CONFIGURE_OPTS to install it with UCS2.
+
 # Use our custom Centos6 image for binary compatibility with old linux distros.
 FROM pantsbuild/centos6:latest