title: Source tree commit attempt fails with cannot amend public changesets error
body: <p>So that I could learn source tree, I set up a private repository in bitbucket and made 2 clones to my computer.
  When I try to commit from one of the clones I get the following error.</p>
  
  <p>hg commit -y --amend --logfile C:\Users\kirsten\AppData\Local\Temp\n1j0esve.5ce
  abort: cannot amend public changesets</p>
  
  <p>Completed with errors, see above.</p>