Updated mediawiki/extensions
Project: mediawiki/extensions/GettingStarted  0477aa472a6a49f943097d6431ea7c44ecb310ca

Don't attempt to log if $revision is null

This is known to occur for null edits, but there are reports at bug
64573 and on IRC that it may also occur in other scenarios.

Fix link to schema.

Bug: 64573
Change-Id: I10cb96b90eb6a6bfafdbf319bc80da5490c1698c