Travis makes us work harder now to actually get OpenJDK 6

SethTisue · SethTisue · commit 1179b7d6d2ed · 2017-10-19T15:59:21.000-05:00
as per: travis-ci/travis-ci#8199 (comment)
diff --git a/.travis.yml b/.travis.yml
@@ -15,6 +15,12 @@ before_install:
   - sudo mv /tmp/hosts /etc/hosts
 script:
   - admin/build.sh
+
+addons:
+  apt:
+    packages:
+      - openjdk-6-jdk
+
 jdk:
   - openjdk6
   - oraclejdk8
