Merge branch 'tr/notes-display'

* tr/notes-display: git-notes(1): add a section about the meaning of history notes: track whether notes_trees were changed at all notes: add shorthand --ref to override GIT_NOTES_REF commit --amend: copy notes to the new commit rebase: support automatic notes copying notes: implement helpers needed for note copying during rewrite notes: implement 'git notes copy --stdin' rebase -i: invoke post-rewrite hook rebase: invoke post-rewrite hook commit --amend: invoke post-rewrite hook Documentation: document post-rewrite hook Support showing notes from more than one notes tree test-lib: unset GIT_NOTES_REF to stop it from influencing tests Conflicts: git-am.sh refs.c