Headers set by MediaWiki are not being set in S3 backend

[Sazpaimon]

I'm setting a Content-Disposition header in mediawiki (to download certain files with their original name and not with underscores). Unfortunately, the S3 client does not properly read these headers, as sanitizeOpHeaders converts all header keys to lowercase, but the S3 backend is hardcoding the expected header names to Content-Disposition and looking for that header in $params['headers']. Ideally, the S3 backend should do something like:

        $params['headers'] += array_fill_keys( [
            'cache-control',
            'content-disposition',
            'content-encoding',
            'content-language',
            'content-type',
            'expires',
            'e-tag',
            'if-modified-since'
        ], null );

to use lowercase keys in order to use any value set by Mediawiki earlier.

[edwardspec]

Problem confirmed. All uses of $params["headers"]["header-name"] in AmazonS3FileBackend::createOrStore() should be made case-insensitive.

[edwardspec]

Should be fixed now.