No, because that is not what is happening. The author is completely misconstruing that information fragment.

  apt-get source <package>

will get you the exact source of the package as released = installed on your system (assuming only one version is present -- otherwise, it returns the newest, but this is configurable).

The message you are seeing is a hint to other developers that the development HEAD is in Bazaar.

This is similar to the relation between GitHub releases, and the master branch.