stg branch -r instructions

It isn't easy to figure out how to rename a branch in stg from looking at the help texts.

  Usage: stg branch [options] branch-name [commit-id]

  ...

    -r, --rename          rename an existing development branch

So, how do I rename branch A to B?

Reading the source, it appears that you write

  stg branch -r A B

so, the usage string is wrong. In fact, the described usage string is only for the default action to create a new branch.

The optparse library doesn't really make it easy to describe these kinds of options-as-subcommands, so I don't have a patch to fix it right away. I'm not even sure how the result should look.

Maybe it would have been better to have separate stg subcommands?

  stg branch NAME [COMMIT]
  stg list-branches
  stg rename-branch OLD NEW
  ... etc ...