rebase -i: respect commit.cleanup when picking fixups

Since f7d42ce (rebase -i: do leave commit message intact in fixup!
chains, 2021-01-28) the sequencer has passed the VERBATIM_MSG flag
when committing the final fixup in a chain. This was added in response
to a bug report[1] where the commit message was being cleaned up when
it should not be. The cause of that bug was that before f7d42ce
the sequencer passed CLEANUP_MSG when committing the final fixup. That
commit should have simply removed the CLEANUP_MSG flag, not changed it
to VERBATIM_MSG. Using VERBATIM_MSG ignores the user's commit.cleanup
config when committing the final fixup which means it behaves
differently to an ordinary "pick" command that respects commit.cleanup.

Fix this by not setting any explicit cleanup flag when committing the
final fixup which matches the way "pick" commands behave. The test
added in f7d42ce is replaced with one that checks that "fixup"
and "pick" commands do not clean up the message when commit.cleanup
is not set and do clean up the message when it is set.

[1] https://lore.kernel.org/git/CANVGpwZGbzYLMeMze64e_OU9p3bjyEgzC5thmNBr6LttBt+YGw@mail.gmail.com/

Signed-off-by: Phillip Wood <[email protected]>

Author: phillipwood

sequencer.c

@@ -2436,7 +2436,6 @@ static int do_pick_commit(struct repository *r,
 		if (!final_fixup)
 			msg_file = rebase_path_squash_msg();
 		else if (file_exists(rebase_path_fixup_msg())) {
-			flags |= VERBATIM_MSG;
 			msg_file = rebase_path_fixup_msg();
 		} else {
 			const char *dest = git_path_squash_msg(r);

t/t3415-rebase-autosquash.sh

@@ -486,12 +486,28 @@ test_expect_success 'fixup a fixup' '
 	test XZWY = $(git show | tr -cd W-Z)
 '
 
-test_expect_success 'fixup does not clean up commit message' '
-	oneline="#818" &&
-	git commit --allow-empty -m "$oneline" &&
-	git commit --fixup HEAD --allow-empty &&
-	git -c commit.cleanup=strip rebase -ki --autosquash HEAD~2 &&
-	test "$oneline" = "$(git show -s --format=%s)"
+test_expect_success 'pick and fixup respect commit.cleanup' '
+	git reset --hard base &&
+	test_commit --no-tag "fixup! second commit" file1 fixup &&
+	test_commit something &&
+	write_script .git/hooks/prepare-commit-msg <<-\EOF &&
+	printf "\n# Prepared\n" >> "$1"
+	EOF
+	git rebase -i --autosquash HEAD~3 &&
+	test_commit_message HEAD~1 <<-\EOF &&
+	second commit
+
+	# Prepared
+	EOF
+	test_commit_message HEAD <<-\EOF &&
+	something
+
+	# Prepared
+	EOF
+	git reset --hard something &&
+	git -c commit.cleanup=strip rebase -i --autosquash HEAD~3 &&
+	test_commit_message HEAD~1 -m "second commit" &&
+	test_commit_message HEAD -m "something"
 '
 
 test_done