Updated mediawiki/extensions
Project: mediawiki/extensions/Wikibase  4f687c83632f88675b0965bf954acbbac93b355b

Clean up MockClientStore

I'm not sure why these objects need to be static. I tried to change
this but some tests failed.

Change-Id: I5313b4f774a6a99c8427a2ea4f783d09f0f39eb3