Fixed thumb.php in r111076. Since WMF still uses thumb-handler.php, the fix has no effect in that case.

Ben, this one is now solely dependent on eliminating ms5 from the thumbnail path, so I'm assigning it to you.

I need to make the tiff/ogg extensions use the ExtractThumbParameters hook in thumb.php as well before we can start using its 404 handling.

(In reply to comment #3)

I need to make the tiff/ogg extensions use the ExtractThumbParameters hook in
thumb.php as well before we can start using its 404 handling.

Done in r111199.

To switch over:
a) 404 handling must be enabled on the scalars to rewrite to thumb_handler.php
b) rewrite.py change to use the scalars directly on 404
c) thumb-handler.php on nginx server could eventually be disabled, though that's not required for this bug

The new handler has been deployed already.