Updated mediawiki/extensions
Project: mediawiki/extensions/UploadWizard  5afe8297cf93114cc21700d7faa1b7412a6f4041
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(bug 37127) UW will not create a category but it tells so

"Is not in use yet" should be neutral enough.
Just "is not in use" could be seen as implying that it shouldn't.
"Does not exist" would be confusing if one doesn't know category pages.

Change-Id: I0a4dcf6345b2a594cfd8128633d6feff108dadfe