What is the purpose of `rmbranch` command?

[Alexander Belchenko]

I thought `rmbranch` should delete a branch from remote server.

It does delete branch (e.g. from shared repository) but leaves .bzr 
control directory there intact.

According to `rmbranch` help it should keep any working tree or 
repository in place. OK, that's good.

But if there is neither working tree nor repository, why don't delete an 
empty control directory?