See PHPUnit\Util\Getopt uses deprecated each() function.
Version 5.7.23 seems to work.
Change 386118 had a related patch set uploaded (by MarkAHershberger; owner: MarkAHershberger):
[mediawiki/core@master] Update phpunit requirement
Change 386118 abandoned by MarkAHershberger:
Update phpunit requirement
abandoning for now, waiting for minimum php 5.6.
Given T178538 (require PHP5.6) was declined and T172165 (require PHP7/HHVM) approved, we can probably upgrade from PHPUnit 4 to PHPUnit 6 directly, and decline this task as well, in favour of T177132.
Declining in favor of jumping directly to PHPUnit 6.x.