title: Force pushing to new head when already pulled all changes
body: <p>Is it possible to forcibly create new remote head when pushing ?</p>
  
  <p>Suppose I have done some local commits on branch "default" then pulled and merged from remote.</p>
  
  <p>Now, I would like to push my commits to remote creating new head and a bookmark but preserve existing remote head and tip - ie. my coworkers should not get my changes yet when doing <code>hg fetch</code>.</p>
  
  <p>Basically this should be a short lived branch (thus not a named branch) for purpose of backup and code review by other before being fully merged into "main" head of default branch.</p>
  
  <p>I've tried <code>--new-branch</code> but it didn't help - no new head was created and remote tip moved to my head.</p>