We should answer the question of differences between aegisco and RBEL repos on the wiki in a more detailed but concise manner. I didn't know that you also maintain V8, nginx, and node.js packages; that's great.
The changes I made for the 18.104.22.1682-1 build were to the underlying build system rather than the spec file (except for bumping the version). I switched to raw rpmbuild with Chef wrapping it, from using mock by hand.
I also re-found an old bug which was annoying to experience: The official ruby RPMs install to /usr/lib and are not effectively cleaned when upgraded. Because ruby defaults to a prefix of /usr/local/lib, this led to inconsistent results. Further, the rubygem package needs to be rebuilt in this case, because it inherits the prefix from ruby.
Another important lesson: do not run build systems on micro instances, especially if you're going to have to re-build many times.