Rudder

We insert the build-time timestamp into the RPM's Epoch field when building packages, in order to ensure that subsequent versions are "greater" in version number than older ones. This is particularly necessary because we do releases like 2.5.0.alpha1, 2.5.0.beta1, 2.5.0, which should be in that order but are not otherwise considered in that order with RPM's version comparaison algorithm. See http://serverfault.com/questions/454462/incremental-rpm-package-version-numbers-for-x-y-z-x-y-z-beta-or-alpha-rc.

The way RPM uses the Epoch field is to prefix it to the Version field, and then compare those as a full version number. This causes problems when upgrading from one major version of Rudder to another, because a 2.5 package may have been built more recently (therefore with a bigger timestamp in the Epoch field) than a 2.6 package.