Superfluous(?) "push -f" warning

[Kai Grossjohann]

Say I have a named branch "unstable" and the default branch is for the 
stable release.  Say further that those developing on the unstable 
branch do "hg merge -r default" often.

Then after they do "hg merge -r default" the default branch loses its 
head and this means that I can't push changes on the default branch 
without using "-f".

But I think if a named branch is headless, then it is not wrong for 
pushing to add a head to this branch.

What do people think?

Kai