In the commit 'MDL-82497 pix: Update SVG icons to align them with FA6' (adb65915da700762af45a52a4f4c4bfab5a7f3fa) the new icons have been added without a default height.

So where blocks/plugins are using the default core image i.e. http://upgrade.vle.norwichuni.ac.uk/theme/image.php?theme=norwich&component=core&image=i%2Floading_small the image loads at 512px x 512px size unless changed in a stylesheet. Is this by design or has the height simply been omitted by mistake?