Last modified: 2007-09-11 18:26:24 UTC
When uploading an image named Image:Example image.jpg an upload warning appears saying that the image name was changed to Image:Example_image.jpg. This should be canceled. The MediaWiki software treats space and underscore exactly the same, (This is a MediaWiki limitation.) so, this warning is meaningless.
It seems to be gone at least as of 1.12.