I build many of the Android apps I use from their source repositories. Since I run Jenkins for continuous building and testing of the programs I work on, I've added these as well. I've been an Android developer for a long time, and on occasion find bugs and submit patches to the upstream projects. This is how the open source community works, we all contribute as we can. Note that as these are built from the master branches, there are no promises on whether any bugs will effect you or not.