[PATCH 0/2 v3] WIP: allow "-" as a shorthand for "previous branch"

[Siddharth Kannan <kannan.siddharth12@gmail.com>]

Thanks a lot, Matthieu, for your comments on an earlier version of this 
patch! [1]

After the discussion there, I have considered the changes that have been made
and I broke them into two separate commits.

I have included the list of commands that are touched by this patch series in
the second commit message. (idea from the v1 discussion [2]) Reproduced here:

  * builtin/blame.c
  * builtin/diff.c
  * builtin/diff-files.c
  * builtin/diff-index.c
  * builtin/diff-tree.c
  * builtin/log.c
  * builtin/rev-list.c
  * builtin/shortlog.c
  * builtin/fast-export.c
  * builtin/fmt-merge-msg.c
  builtin/add.c
  builtin/checkout.c
  builtin/commit.c
  builtin/merge.c
  builtin/pack-objects.c
  builtin/revert.c

  * marked commands are information-only.

I have added the WIP tag because I am still unsure if the tests that I have
added (for git-log) are sufficient for this patch or more comprehensive tests
need to be added. So, please help me with some feedback on that.

I have removed the "log:" tag from the subject line because this patch now
affects commands other than log.

I have run the test suite locally and on Travis CI! [3]

[1]: https://public-inbox.org/git/vpqh944eof7.fsf@anie.imag.fr/#t
[2]: https://public-inbox.org/git/CAN-3QhoZN_wYvqbVdU_c1h4vUOaT5FOBFL7k+FemNpqkxjWDDA@mail.gmail.com/
[3]: https://travis-ci.org/icyflame/git/builds/200431159

Siddharth Kannan (2):
  revision.c: args starting with "-" might be a revision
  sha1_name: teach get_sha1_1 "-" shorthand for "@{-1}"

 revision.c               | 12 ++++++--
 sha1_name.c              |  5 ++++
 t/t4214-log-shorthand.sh | 73 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 88 insertions(+), 2 deletions(-)
 create mode 100755 t/t4214-log-shorthand.sh

-- 
2.1.4