Replaces \TestingAccessWrapper (defined in core) with
\Wikimedia\TestingAccessWrapper (defined in the composer package
wikimedia/testing-access-wrapper).
See https://gerrit.wikimedia.org/r/#/q/topic:librarize-testing-access-wrapper
for downstream patches.
The core version of the class is kept around for a while to avoid
circular dependency problems.
Bug: T163434
Change-Id: I52cc257e593da3d6c3b01a909e554a950225aec8
Follows-up c4e698dc2. The tests are failing on Travis CI because
php5-redis isn't installed by default. These tests shouldn't need
that to be installed (and even then, we should skip gracefully as
it is an optional dependency).
> RedisBagOStuffTest::testUnserialize with data set #0
> Exception: RedisConnectionPool requires a Redis client library.
> ./mediawiki/includes/clientpool/RedisConnectionPool.php:86
Fixed by using a mock and disabling the original constructor.
Change-Id: Icced7c30a75516c2118489ad29eac2aa5cff80ad
