TYPO3 Core

I have found a very similar issue. So I add it here.
If a user loads translations from the translation server, and if there are no translations available, then all translations coming from the extension's files and setup are removed. And not even the default language is used.

E.g you have the translation files in the folder
/typo3conf/l10n/de/tt_products

All translated values in the file de.locallang_db.xml are empty:

<?xml version="1.0" encoding="UTF-8"?>
<T3locallangExt>
  <data type="array">
    <languageKey index="de" type="array">
            <label index="tstamp"/>
            <label index="crdate"/>
            <label index="tt_products"/>
            <label index="tt_products.accessory_uid"/>
            <label index="tt_products.prod_uid"/>
            <label index="tt_products.related_uid"/>
            <label index="tt_products.price"/>
            <label index="tt_products.price2"/>
            <label index="tt_products.unit"/>
            <label index="tt_products.unit_factor"/>
            <label index="tt_products.graduated_price_uid"/>
            <label index="tt_products.note_uid"/>
            <label index="tt_products.note"/>

        <languageKey index="de" type="array">
            <label index="tstamp">Zeitstempel</label>
            <label index="crdate">Bestelldatum</label>
            <label index="tt_products">Produkte</label>
            <label index="tt_products.prod_uid">Template Produkte</label>
            <label index="tt_products.accessory_uid">Zubehör</label>
            <label index="tt_products.related_uid">verwandte Produkte</label>
            <label index="tt_products.price">Preis:</label>
            <label index="tt_products.price2">Preis (2):</label>
            <label index="tt_products.discount">Möglicher Rabatt:</label>

So the function readLLXMLfile removes all the already read in translations. This breaks the extension in the FE and BE and makes it unusable for all languages except English.

I have attached a patch which fixes this issue for TYPO3 4.5.30.

Patch set 1 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at http://review.typo3.org/35948

Applied in changeset 262bdeeb9a4b6fe362c9fcd2d547db0409424c7a.