Merge branch 'js/rebase-i-root-fix'

A regression to "rebase -i --root" introduced during this cycle has
been fixed.

* js/rebase-i-root-fix:
  rebase --root: fix amending root commit messages
  rebase --root: demonstrate a bug while amending root commit messages

sequencer.c

@@ -784,7 +784,7 @@ static int run_git_commit(const char *defmsg, struct replay_opts *opts,
 	struct child_process cmd = CHILD_PROCESS_INIT;
 	const char *value;
 
-	if (flags & CREATE_ROOT_COMMIT) {
+	if ((flags & CREATE_ROOT_COMMIT) && !(flags & AMEND_MSG)) {
 		struct strbuf msg = STRBUF_INIT, script = STRBUF_INIT;
 		const char *author = is_rebase_i(opts) ?
 			read_author_ident(&script) : NULL;

t/t3404-rebase-interactive.sh

@@ -971,6 +971,15 @@ test_expect_success 'rebase -i --root fixup root commit' '
 	test 0 = $(git cat-file commit HEAD | grep -c ^parent\ )
 '
 
+test_expect_success 'rebase -i --root reword root commit' '
+	test_when_finished "test_might_fail git rebase --abort" &&
+	git checkout -b reword-root-branch master &&
+	set_fake_editor &&
+	FAKE_LINES="reword 1 2" FAKE_COMMIT_MESSAGE="A changed" \
+	git rebase -i --root &&
+	git show HEAD^ | grep "A changed"
+'
+
 test_expect_success C_LOCALE_OUTPUT 'rebase --edit-todo does not work on non-interactive rebase' '
 	git reset --hard &&
 	git checkout conflict-branch &&