A lot of ROS packages such as MoveIt! have in the past relied on Travis' free continuous integration services for testing pull requests/commits on Github. However, this has mostly been broken for ROS for the past couple years since Travis had not upgraded to Ubuntu 14.04, and ROS Indigo+ requires it. This problem was discussed recently at ROSCon '15. 

Hurray for code testing!

p.s. I am not affiliated with Travis