"git branch --list" learned to show its output through the pager by
default when the output is going to a terminal, which is controlled
by the pager.branch configuration variable.  This is similar to a
recent change to "git tag --list".

* ma/branch-list-paginate:
  branch: change default of `pager.branch` to "on"
  branch: respect `pager.branch` in list-mode only
  t7006: add tests for how git branch paginates