zendframework/zf2 — pull request #3505 by superdweebie (2013-01-21 00:24:07+00:00)
Title: Give StdLib\ArrayUtils::merge the ability to remove keys

The motivation for this change is to make is possible to unregister config keys when ModuleManager merges all config arrays together.

At present the 'magic' value for key removal is `__remove__`.

See also http://stackoverflow.com/questions/14423983/zf2-modulemanager-config-merge-remove-key