Instead of escaping in two locations, how about we perform `git_branch` overriding in an `if` check?

```
git_branch = settings.get('branch')
if branch is None:
  # Strip away `refs/head` that Phab dislikes
  # `refs/heads/dev/my.branch` -> `dev/my.branch`
  git_branch = git_stdout.replace(...)

# Double escape branch name for Phab
# `dev/my.branch` -> `dev%2Fmy.branch` -> `dev%252Fmy.branch`
escaped_branch = escaped_branch = quote(quote(settings.get('branch'), safe=''), safe='')
```