fix java 6 build on travis by using precise distribution

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/exec/trunk@1811466 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/.travis.yml b/.travis.yml
index c68bfd2..2cdda93 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -16,6 +16,8 @@
 language: java

 sudo: true

 

+dist: precise

+

 jdk:

   - openjdk6

   - openjdk7