Wordpress 3.5 breaking change on IIS 7.5 - download failed...

I recently upgrade this blog to WP 3.5 and all looked fine. However, when I tried to update the akismet plugin, it would fail with “Download failed. Destination directory for file streaming does not exist or is not writable..”  Most search results indicated a permissions issue, but I hadn’t changed any permissions.  Thankfully I found a post related which pointed me to this defect with the appropriate workaround. Basically, there was a regression in 3.5 related to what temp folder was used - and even though there’s a fix in 3.5.1, it’s a chicken and egg problem since downloading 3.5.1 would fail due since pointing to the wrong temp folder.

I added this to my wp-config.php and was able to update the plugin just fine.

define( 'WP_TEMP_DIR', ABSPATH . 'wp-content/' );