[FS#531] dokuwiki: login with github returns 404

[LEDE Bugs]

The following task has a new comment added:

FS#531 - dokuwiki: login with github returns 404
User who did this - Jo-Philipp Wich (jow-)

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The empty "&state=" param appeneded by Github seemed to trip up Dokuwiki's oauth plugin. I added some workarounds in Nginx now to filter away the empty "&state=" query string param in order to avoid patching the PHP code itself.

With the workaround applied, Github logins appear to work fine again.
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=531#comment1892