[GSoC][PATCH v5 0/3] rebase -i: rewrite reflog operations in C

This patch series rewrites the reflog operations from shell to C. This is part of the effort to rewrite interactive rebase in C.

The first commit is dedicated to creating a function to silence a command, as the sequencer will do in several places with these patches.

This branch is based on ag/rebase-i-rewrite-todo, and does not conflict with pu (as of 2018-06-29).

Changes since v4:

 - Changing the order of setup_reflog_action() and checkout_onto()
   rewrites in the series

 - checkout_onto() is no longer renamed in C

 - setup_reflog_action() is renamed to prepare_branch_to_be_rebased(),
   and not to checkout_onto().

Alban Gruin (3):
  sequencer: add a new function to silence a command, except if it
    fails.
  rebase -i: rewrite setup_reflog_action() in C
  rebase -i: rewrite checkout_onto() in C

 builtin/rebase--helper.c   |  14 ++++-
 git-rebase--interactive.sh |  39 ++------------
 sequencer.c                | 101 +++++++++++++++++++++++++++----------
 sequencer.h                |   6 +++
 4 files changed, 98 insertions(+), 62 deletions(-)