Trying to clean my repo... help?

[Matt Chaput]

> The fundamental thing to understand is that 'push' and 'pull' will never
> _remove_ changesets, they'll only add. So nothing you can do from the hg
> command line can make an already pushed commit disappear from a remote
> machine. So you need to blow away all or part of your repo on Bitbucket
> 'manually'.

Is there at least some way to get hg to stop thinking that the changeset
before I named the branch is a dangling extra head in the default branch?

Thanks,

Matt