push aborts for new branch even if no heads

[Jesse Glick]

Dirkjan Ochtman wrote:
>> Closed branches should be pushable with no flag at all
> 
> This works well today, with hg 1.3.1, by using --close-branch and then
> merging the closing commit into some other branch.

Assuming "some other branch" means "default", that's no good because it makes the default branch dependent on all the closed branches. These are probably no longer 
critical to have except for archival purposes. So if someone does 'hg clone -r default' they will get all of these closed branches by way of dummy merges.

I suppose you could have a special branch called "void" whose sole purpose was to serve as a (dummy) merge point for closed branches. But it seems simpler, nicer, and 
more intuitive to just close a branch and have it disappear from view unless someone is really looking for it.