Function is_fixup_flag

sequencer.c:1895–1899

static const char combined_commit_msg_fmt[] = N_("This is a combination of %d commits.");

static int is_fixup_flag(enum todo_command command, unsigned flag)
{
	return command == TODO_FIXUP && ((flag & TODO_REPLACE_FIXUP_MSG) ||
					 (flag & TODO_EDIT_FIXUP_MSG));
}

/*
 * Wrapper around strbuf_add_commented_lines() which avoids double