Travis makes us work harder now to actually get OpenJDK 6

SethTisue · SethTisue · commit 90ea0dd4280a · 2017-10-19T12:27:57.000-05:00
as per: travis-ci/travis-ci#8199 (comment)
diff --git a/.travis.yml b/.travis.yml
@@ -28,6 +28,11 @@ env:
 
 script: admin/build.sh
 
+addons:
+  apt:
+    packages:
+      - openjdk-6-jdk
+
 jdk:
   - openjdk6
   - oraclejdk8
