Merge branch 'jk/show-upstream'

* jk/show-upstream:
  branch: show upstream branch when double verbose
  make get_short_ref a public function
  for-each-ref: add "upstream" format field
  for-each-ref: refactor refname handling
  for-each-ref: refactor get_short_ref function

diff --cc refs.c
Simple merge

diff --cc refs.h
Simple merge