hg-git: push -d default seems not to work.

[Uwe Brauer]

   > Why do you merge it? Generally when you're submitting code upstream,
   > you'd submit just your branch. The maintainer of the project will
   > apply your patches or merge your branch.

Because they want clean 'clutter free' commits and they don't want
branches to be pushed. I could use rebase with the collapse option,
but then I will not really understand the graph in the future.