Comment 7 for bug 209515

This is especially bad when releasing an rc before the next official release. For example, right now we have 1.3.1, and 1.4rc2. We should still allow people to install 1.3.1 since it is the last officially stable release. Further, it is likely that we do not have matching release candidates for 3rd party software present in the same archive. (bzrtools doesn't release a new version until 1.x-final is out, same for bzr-gtk)