Wikibase-related gate and submit tests are failing due to issues with scribunto:
https://integration.wikimedia.org/ci/job/mwext-testextension-php55-composer-trusty/151/console
```
03:32:45 153) LuaStandalone: LuaWikibaseLibraryTests[38]: mw.wikibase.resolvePropertyId (label not found)
03:32:45 proc_open(): fork failed - Cannot allocate memory
03:32:45
03:32:45 /home/jenkins/workspace/mwext-testextension-php55-composer-trusty/src/extensions/Scribunto/engines/LuaStandalone/LuaStandaloneEngine.php:267
03:32:45 /home/jenkins/workspace/mwext-testextension-php55-composer-trusty/src/extensions/Scribunto/engines/LuaStandalone/LuaStandaloneEngine.php:115
03:32:45 /home/jenkins/workspace/mwext-testextension-php55-composer-trusty/src/extensions/Scribunto/engines/LuaCommon/LuaCommon.php:95
03:32:45 /home/jenkins/workspace/mwext-testextension-php55-composer-trusty/src/extensions/Scribunto/engines/LuaStandalone/LuaStandaloneEngine.php:9
03:32:45 /home/jenkins/workspace/mwext-testextension-php55-composer-trusty/src/extensions/Scribunto/engines/LuaCommon/LuaCommon.php:198
03:32:45 /home/jenkins/workspace/mwext-testextension-php55-composer-trusty/src/extensions/Scribunto/engines/LuaCommon/LuaCommon.php:884
03:32:45 /home/jenkins/workspace/mwext-testextension-php55-composer-trusty/src/extensions/Scribunto/tests/engines/LuaCommon/LuaDataProvider.php:21
03:32:45 /home/jenkins/workspace/mwext-testextension-php55-composer-trusty/src/extensions/Scribunto/tests/engines/LuaCommon/LuaEngineTestBase.php:237
03:32:45 /home/jenkins/workspace/mwext-testextension-php55-composer-trusty/src/extensions/Scribunto/tests/engines/LuaCommon/LuaEngineTestBase.php:249
03:32:45 /home/jenkins/workspace/mwext-testextension-php55-composer-trusty/src/tests/phpunit/MediaWikiTestCase.php:400
03:32:45 /home/jenkins/workspace/mwext-testextension-php55-composer-trusty/src/maintenance/doMaintenance.php:111
```
this is using 1.8G of memory (same tests on hhvm use 610mb), so could be a memory leak or something. I'm not sure if we can fix in the code or not.
1016.3283 1799.0M Scribunto_LuaStandaloneInterpreter::terminate: terminating
https://integration.wikimedia.org/ci/job/mwext-testextension-php55-composer-trusty/160/artifact/log/mw-debug-cli.log/*view*/