XPoll application is displayed in German when wiki language is set to French

[lucaa]

How to reproduce:

• set the wiki language to French in the administration
• install the XPoll application

Expected result:

• the XPoll application is displayed in French

Actual result:

• the XPoll application is displayed in German

[lucaa]

Since after install in the wiki itself the document with german text appears as having the french language and the "de" translation does not appear in the package.xml of the xar of the application, I suspect the cause to be the locale='fr' on this line https://github.com/xwikisas/application-xpoll/blob/master/application-xpoll-ui/src/main/resources/XPoll/Translation.de.xml#L23 .
I assume this is what makes the reference of the page (not the tag lower in this document), and this is why that file gets imported as the french translation.