On which occasions will the registration ID for a C2DM client change?

In the documentation for push on Android it states that one has to implement the registration logic in a way that is capable of handling changes to the registration ID by Google. In the scenario I want to realize, this adds a lot of complexity, since I want to send push notifications from a build server, not an application server, and it looks like I cannot rely on the registration ID to be stable.

Has this actually ever happened to you that the Google push servers would send a new registration ID to your client, or is a case where Google simply want to reserve some flexibility for themselves? If it happened, how frequently? Ideally I would like to register my client application once, and then configure the build ser开发者_运维问答ver with the static registration ID.