Detected when importing recent MediaWiki dumps containing some pages
with script content in plain text format (see Scribunto extension
https://www.mediawiki.org/wiki/Extension:Scribunto ).
Further improvement : modify the MediawikiImporter to prevent processing
revisions whose <model> is not wikitext.
be translated. To avoid key="TEST" sourcetext="this is a myTESTcase for it"
translation of partial terms/words.
Add check of word boundary before and after sourcetext (incl. take care
of current praxis for key to be delimetered by > <
+ add test case
