Comment 1 for bug 423447

This one is slightly tricky because we'd need to explain to the user that they've got a Launchpad account and an SSO one, and in order to merge them they'd have to "upgrade" that SSO one into a Launchpad one (by logging into LP using the SSO credentials) and then merging the two. That's far from ideal, so we might want to make it possible to merge an SSO account into a LP one before we fix this.