silverstripe/silverstripe-framework — pull request #3496 by halkyon (2014-09-18 21:25:44+00:00)
Title: BUG If config key doesn't exist, false config vals aren't set.

Config::merge_array_low_into_high() will ignore false values that
don't exist in the config already. The expectation is that if the
key isn't set, you can still set a false value, just not overwrite
the true value with a false one when merging into an existing.

Added some tests to verify that merging still works as expected.