[PATCH 0/2] commit: preserve commit hash on a no-op amend

["Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com>]

git commit --amend --no-edit rewrote the commit and moved the branch tip
even when nothing changed, because the committer date was reset to "now".
Reuse the existing committer date so a no-op amend keeps the commit hash and
leaves the branch untouched.

A real change (tree, message, author, committer, or signing) still rewrites
as before.

Harald Nordgren (2):
  commit: extract commit_index_files_or_die() helper
  commit: keep the commit on a no-op amend

 Documentation/git-commit.adoc         |   6 ++
 builtin/commit.c                      |  69 ++++++++++++++-
 t/t7501-commit-basic-functionality.sh | 119 ++++++++++++++++++++++++++
 3 files changed, 190 insertions(+), 4 deletions(-)


base-commit: ea97ad8d017de0c9037451a78008a0fd60abea0c
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2334%2FHaraldNordgren%2Famend-noop-keeps-commit-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2334/HaraldNordgren/amend-noop-keeps-commit-v1
Pull-Request: https://github.com/git/git/pull/2334
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