Fix lua backend, which ignored first running entry

Summary: Before, lua backend was launched with worksheet loading and have time for parsing lua start information (`Lua 5.2.4  Copyright (C) 1994-2015 Lua.org, PUC-Rio`). But now, first command go to lua, before start information parsing and this leads, that output of this command erroneously be removed. So I add @asemke suggestion, that solve this problem.

Test Plan:
1) Run lua backend without patch and check, that first runned entry haven't output result.
2) Apply patch
3) Check, that now first runned entry have output result.

Reviewers: #cantor

Subscribers: asemke, #cantor, #kde_edu

Tags: #kde_edu, #cantor

Differential Revision: https://phabricator.kde.org/D11792