replaceExternalLinks removes wrong closing square bracket with nested internal link about wikiextractor

[spyysalo]

I looked at this a bit more, and the issue appears to be this regex: https://github.com/attardi/wikiextractor/blob/master/WikiExtractor.py#L2039, in particular the part

([^\]\x00-\x08\x0a-\x1F]*?)\]

which eats left square brackets (only ] appears in the negated character class) and terminates on the first closing bracket.

It should be possible to fix with the following pattern (here writingBADCHARS for \x00-\x08\x0a-\x1F for readability)

((?:[^][BADCHARS]|\[\[[^][BADCHARS]*\]\])*?)\]

Would you consider a pull request implementing this?

[attardi]

Alternatively one may look for the first ] which is not followed by another ], i.e.:

'](?!])'

Please try it and let me know.