Wikimedia Bugzilla is closed!

Math.php was recently changed to use 3 levels of subdirectories for the rendered math 
images. Unfortunately the code is broken such that initial rendering is done into the 
wrong directory, so any newly rendered images end up in the wrong directory and aren't 
visible (404).

For instance rendering this bit in the english wikipedia sandbox:
<math>\frac{238490}{89973}</math>

gives this URL:
http://en.wikipedia.org/math/4/8/2/48287d2c5dacab82a7a4b46638ee6781.png

but the file is actually at:
http://en.wikipedia.org/math/48287d2c5dacab82a7a4b46638ee6781.png

The subdirectories are the first three digits of the hex output content hash, which is 
used to name the .png files. This value is calculated by texvc, so is not known until 
after texvc returns, but we try to generate the directory and pass it to texvc to tell it 
where to deposit the image... This ends up trying something like "/math///" which reduces 
in Unix semantics to "/math/".

Recommendation: render into the temp directory, then move the image to its final 
destination.