When building magento with MYSQL56 enabled, the compiler cannot find the following file:
/usr/ports/www/magento/files/extra-patch-app__code__core__Mage__Install__Model__Installer__Db__Mysql4.php

I can confirm that the file does *not* exist.

Not enabling this patch prevents magento from working with mysql56 (the current version in ports). The only alternative is to use Mysql55 (which still supports InnoDB)

Fix: 

Workaround:
Install MySQL55 instead of MySQL56 (the current version).

Easy fix:
Put the file back.

Update available:
I also noticed that magento 1.8 has been released which fixes the problem that this patch is for. Perhaps updating the port to 1.8 would be a better solution.
How-To-Repeat: go to /usr/ports/www/magento
run "make config" and set MYSQL56 to true
run "make"


===== Output Below =====

===>  Found saved configuration for magento-1.7.0.2
===> Fetching all distfiles required by magento-1.7.0.2 for building
===>  Extracting for magento-1.7.0.2
=> SHA256 Checksum OK for magento-1.7.0.2.tar.gz.
===>  Patching for magento-1.7.0.2
===>  Applying extra patch /usr/ports/www/magento/files/extra-patch-app__code__core__Mage__Install__Model__Installer__Db__Mysql4.php
cat: /usr/ports/www/magento/files/extra-patch-app__code__core__Mage__Install__Model__Installer__Db__Mysql4.php: No such file or directory
  I can't seem to find a patch in there anywhere.
===>  Configuring for magento-1.7.0.2