[PATCH 0/2] shortlog: introduce --email-only, --group-filter options

These couple of patches introduce a pair of new options to `git shortlog`. They are:

  - `--group-filter`, which restricts the output to group(s) of interest

  - `--email-only`, which allows callers to splice emails out of groups,
    which is useful when grouping based on trailers that usually contain
    identities (e.g. "Co-authored-by"), where the search is
    name-insensitive and only cares about a strict match on the email.

Let me know what you think, and thanks in advance for your review.

Taylor Blau (2):
  shortlog: introduce `--group-filter` to restrict output
  shortlog: introduce `--email-only` to only show emails

 Documentation/git-shortlog.txt | 10 +++++
 builtin/shortlog.c             | 53 +++++++++++++++++-----
 shortlog.h                     |  3 ++
 t/t4201-shortlog.sh            | 82 ++++++++++++++++++++++++++++++++++
 4 files changed, 138 insertions(+), 10 deletions(-)