[PATCH v2] rebase -i: fix rewording with --committer-date-is-author-date

["Phillip Wood via GitGitGadget" <gitgitgadget@gmail.com>]

From: Phillip Wood <phillip.wood@dunelm.org.uk>

baf8ec8d3a (rebase -r: don't write .git/MERGE_MSG when
fast-forwarding, 2021-08-20) stopped reading the author script in
run_git_commit() when rewording a commit. This is normally safe
because "git commit --amend" preserves the authorship. However if the
user passes "--committer-date-is-author-date" then we need to read the
author date from the author script when rewording. Fix this regression
by tightening the check for when it is safe to skip reading the author
script.

Reported-by: Jonas Kittner <jonas.kittner@ruhr-uni-bochum.de>
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
---
    rebase -i: fix rewording with --committer-date-is-author-date
    
    This regression was introduced in the current cycle and is present in
    v2.34.0-rc0, v2.33.1 and maint
    
    Thanks to Jonas for reporting it and Peff for bisecting

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1123%2Fphillipwood%2Fwip%2Frebase-committer-date-is-author-date-fix-reword-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1123/phillipwood/wip/rebase-committer-date-is-author-date-fix-reword-v2
Pull-Request: https://github.com/git/git/pull/1123

Range-diff vs v1:

 1:  fb88c58d2fb ! 1:  6565c02ba89 rebase -i: fix rewording with --committer-date-is-author-date
     @@ Commit message
          by tightening the check for when it is safe to skip reading the author
          script.
      
     +    Reported-by: Jonas Kittner <jonas.kittner@ruhr-uni-bochum.de>
          Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
      
       ## sequencer.c ##


 sequencer.c                    |  4 +++-
 t/t3436-rebase-more-options.sh | 29 +++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/sequencer.c b/sequencer.c
index cd2aabf1f76..ea96837cde3 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -997,7 +997,9 @@ static int run_git_commit(const char *defmsg,
 
 	cmd.git_cmd = 1;
 
-	if (is_rebase_i(opts) && !(!defmsg && (flags & AMEND_MSG)) &&
+	if (is_rebase_i(opts) &&
+	    ((opts->committer_date_is_author_date && !opts->ignore_date) ||
+	     !(!defmsg && (flags & AMEND_MSG))) &&
 	    read_env_script(&cmd.env_array)) {
 		const char *gpg_opt = gpg_sign_opt_quoted(opts);
 
diff --git a/t/t3436-rebase-more-options.sh b/t/t3436-rebase-more-options.sh
index 4d106642ba7..94671d3c465 100755
--- a/t/t3436-rebase-more-options.sh
+++ b/t/t3436-rebase-more-options.sh
@@ -82,6 +82,20 @@ test_expect_success '--committer-date-is-author-date works with merge backend' '
 	test_ctime_is_atime -1
 '
 
+test_expect_success '--committer-date-is-author-date works when rewording' '
+	GIT_AUTHOR_DATE="@1234 +0300" git commit --amend --reset-author &&
+	(
+		set_fake_editor &&
+		FAKE_COMMIT_MESSAGE=edited \
+			FAKE_LINES="reword 1" \
+			git rebase -i --committer-date-is-author-date HEAD^
+	) &&
+	test_write_lines edited "" >expect &&
+	git log --format="%B" -1 >actual &&
+	test_cmp expect actual &&
+	test_ctime_is_atime -1
+'
+
 test_expect_success '--committer-date-is-author-date works with rebase -r' '
 	git checkout side &&
 	GIT_AUTHOR_DATE="@1234 +0300" git merge --no-ff commit3 &&
@@ -155,6 +169,21 @@ test_expect_success '--reset-author-date with --committer-date-is-author-date wo
 	test_atime_is_ignored -2
 '
 
+test_expect_success 'reset-author-date with --committer-date-is-author-date works when rewording' '
+	GIT_AUTHOR_DATE="@1234 +0300" git commit --amend --reset-author &&
+	(
+		set_fake_editor &&
+		FAKE_COMMIT_MESSAGE=edited \
+			FAKE_LINES="reword 1" \
+			git rebase -i --committer-date-is-author-date \
+				--reset-author-date HEAD^
+	) &&
+	test_write_lines edited "" >expect &&
+	git log --format="%B" -1 >actual &&
+	test_cmp expect actual &&
+	test_atime_is_ignored -1
+'
+
 test_expect_success '--reset-author-date --committer-date-is-author-date works when forking merge' '
 	GIT_SEQUENCE_EDITOR="echo \"merge -C $(git rev-parse HEAD) commit3\">" \
 		PATH="./test-bin:$PATH" git rebase -i --strategy=test \

base-commit: 0cddd84c9f3e9c3d793ec93034ef679335f35e49
-- 
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