[PATCH v6 00/13] Finish converting git bisect to C part 2

These patches correspond to a second part of patch series of Outreachy project "Finish converting `git bisect` from shell to C" started by Pranit Bauva and Tanushree Tumane (https://public-inbox.org/git/pull.117.git.gitgitgadget@gmail.com) and continued by me.

These patch series emails were generated from: https://gitlab.com/mirucam/git/commits/git-bisect-work-part2-v6ps.

I would like to thank the reviewers for their help.

General changes ---------------

* Rebase on master branch: e9b77c84a0 (Tenth batch, 2020-08-24)

Specific changes ----------------

[1/13] bisect--helper: BUG() in cmd_*() on invalid subcommand

* Amend commit message.
* Remove casting to int.

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[2/13] bisect--helper: use '-res' in 'cmd_bisect__helper' return

* Amend commit message.

---

[3/13] bisect--helper: introduce new `write_in_file()` function

* Use saved_errno variable.

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[5/13] bisect--helper: reimplement `bisect_autostart` shell function in C

* Fix bug using empty_strvec instead of NULL in a `bisect_start()` call.

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[6/13] bisect--helper: reimplement `bisect_next` and `bisect_auto_next` shell
 functions in C
 
* Change `file_exists(git_path_bisect_head())` to a refs API call.
 
---

Miriam Rubio (4):
  bisect--helper: BUG() in cmd_*() on invalid subcommand
  bisect--helper: use '-res' in 'cmd_bisect__helper' return
  bisect--helper: introduce new `write_in_file()` function
  bisect: call 'clear_commit_marks_all()' in 'bisect_next_all()'

Pranit Bauva (9):
  bisect--helper: reimplement `bisect_autostart` shell function in C
  bisect--helper: reimplement `bisect_next` and `bisect_auto_next` shell
    functions in C
  bisect--helper: finish porting `bisect_start()` to C
  bisect--helper: retire `--bisect-clean-state` subcommand
  bisect--helper: retire `--next-all` subcommand
  bisect--helper: reimplement `bisect_state` & `bisect_head` shell
    functions in C
  bisect--helper: retire `--check-expected-revs` subcommand
  bisect--helper: retire `--write-terms` subcommand
  bisect--helper: retire `--bisect-autostart` subcommand

 bisect.c                 |   8 +
 builtin/bisect--helper.c | 445 ++++++++++++++++++++++++++++++++-------
 git-bisect.sh            | 145 +------------
 3 files changed, 380 insertions(+), 218 deletions(-)