Add second command to checkout an existing branch

Problem/Motivation

When working on multiple issues you will switch branches several times.
When you have a pre-existing branch you either have to copy the checkout command then delete the track and -b option, or remember the issue id.

It would be great to have a second option for checking out a branch that you already have.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes