Rebase an old branch and it suddenly looks recent again. The rewritten tip gets a fresh committer date.
```
[rebase]
instructionFormat = %s%nexec GIT_COMMITTER_DATE=\"%cI\" GIT_COMMITTER_NAME=\"%cN\" GIT_COMMITTER_EMAIL=\"%cE\" git commit --amend --no-edit%n
committerDateIsAuthorDate = true
```