Local:
$ git for-each-ref --sort=-committerdate --format='%(committerdate:iso8601) %(objectname:short) %(refname)' refs/heads
Remote:
$ git for-each-ref --sort=-committerdate --format='%(committerdate:iso8601) %(objectname:short) %(refname)' refs/remotes/upstream
Local:
$ git branch --merged
Remote:
$ git branch -r --merged master upstream/\*
$ comm -12 <(git branch --merged | cut -c3-) <(git branch -r --merged master upstream/\* | cut -d/ -f2)
Merged remote branches, sorted by date of last commit:
$ for i in $(git branch -r --merged master upstream/\*); do git for-each-ref --format='%(committerdate:iso8601) %(objectname:short) %(refname)' refs/remotes/$i; done | sort -n